Suggestion:

Find a comfortable place (quiet if possible) and read through this tutorial one time without worrying about whether or not you understand it or will remember it all. 

Open Painter and read it again, referring to the Painter interface to see where things are (main Menu items, Palettes, Palette sections, and Palette section menus referred to in this tutorial) . 

After doing both of the above, have a try at opening a new Canvas and working with Layers (Floaters/Transparent Layers) on an image used just for the purpose of learning. 

When you finish this tutorial, please also read and use the tutorial named:

A description is found at the end of this page, along with another link so you don't have to scroll back up to the top again.

It's unlikely that you'll find a single tutorial that covers everything about Layers (Painter 6) and Floaters/Transparent Layers (Painter 5/5.5) as there's a lot to know. Reading the Painter 5, 5.5 or 6 User Guide (for Painter 5 and 5.5, if you don't have a hard copy, you should probably have a PDF file on the CD) and the Help menu PDF files (Painter 5 Help menu Index) will give you a tremendous amount of good information. Try to get into the habit of referring to them. In a fairly short time, you'll begin to know where to look for specific things and know more of the terminology used to find them, another thing that just takes time and practice. 

Here are some basics based on questions people have posed in various Painter related gathering places and general information you need to know:

Any painted areas of your Layers (Painter 5/5.5 Floaters/Transparent Layers) will prevent you from seeing what's below them on other Layers and the Canvas (other Painter 5/5.5 Floaters/Transparent Layers and the Canvas). Only the un-Filled and unpainted areas will be transparent. If your Layer (Floater) was made using a Selection of the entire Canvas, the entire Layer (Floater) will be opaque, including the painted or Filled areas and the remaining Canvas color. The Canvas is always whatever color you chose when creating the New Canvas, or whatever color you used to Fill and paint it. If you want to see what's below your Layer (Floater/Transparent Layer), in the Objects palette's Layers section list (Floater section list), highlight the appropriate Layer (Floater/Transparent Layer) and click its Eye icon to temporarily close it. 

There's another important thing to remember. If your Layer (Floater) was created by painting on part of the Canvas, using Select/All, then clicking inside the Selection with the Layer Adjuster tool (Floater Adjuster tool), the unpainted parts of the Layer (Floater) will be opaque and whatever color the (former) Canvas was. If the Canvas was white, there's a way to make the white areas of the Layer (Floater) transparent (temporarily or permanently if you choose to leave it that way):

1. Click the Layer Adjuster tool (Floater Adjuster tool) and, in the Layer list (Floater list), highlight the appropriate Layer (Floater).

2. In the Controls:Adjuster palette (Ctrl/Command+5 to toggle it open and closed), choose Gel or Multiply from the Composite Method drop down list. You can change it back by choosing the Composite Method Default any time you want to as long as the image is still a RIFF file and therefore contains Painter specific information such as Layers  (Floaters/Transparent Layers), etc. 

To see the actual size of your Layer (Floater/Transparent Layer), in the Layers list (Floater list), highlight the appropriate Layer (Floater) then in the Layers menu (Floater menu), choose Show Layer Marquee (Show Floater Marquee). A black and yellow bounding box is displayed. To turn it off, choose Hide Layer Marquee (Hide Floater Marquee). 

To paint outside of the existing Floater's/Transparent Layer's painted area, change your Brush Variant's Method to Plugin and the Subcategory to Transparent Layer Brush. 

NOTE: You'll have to change these settings each time you switch to another Brush Variant.

Using Transparent Layers:

In the Objects palette's Floater section menu, choose Transparent Layer and paint with the Brush Variants' Method set to Plugin and the Subcategory set to Transparent Layer Brush. 

NOTE: Use the other Subcategory options to paint effects on existing areas painted with the Transparent Layer Brush.

If you click on the center of a Layer (Floater/Transparent Layer) and it "turns white", it could be because the appropriate Layer (Floater/Transparent Layer) was not highlighted in the Layers (Floaters) list. In other words, it was not active. Instead, the Canvas was active and part or all of the Canvas was selected (had "marching ants" around it). 

To know when the Canvas is active, look in the Layers section list (Floaters section list). If the Canvas is highlighted, it's active. 

(Painter 5/5.5: If no Floater/Transparent Layer is highlighted, the Canvas is active. To make the Canvas active when a Floater/Transparent Layer is highlighted, click in the blank area below the list of Floaters/Transparent Layers.)

OOPS! I made a mistake. Now what?

To revert to the previous state of your image, in the Edit menu, choose Undo (or use  Ctrl/Command+Z) to Undo the last action. Repeat this step to Undo as many previous actions as you want (up to the number you've chosen to make available). The default number of Undos is fairly small. However, you can set the number to a maximum of 32 Undos. Remember, though, that the higher the number the more memory is used. To change this setting, go to the Edit menu, choose Preferences, choose Undo, and type the number of Undos you want.

I hope that this tutorial contains enough information to help you with the basics of using Layers (Floaters/Transparent Layers).

If not, please feel free to ask specific questions including the Painter version you're using and any patches you've installed. In your questions, try to use the terminology you see in the Painter Interface whenever possible. This will make it easier for people to understand your questions and respond to them properly. 

Reading and working this tutorial and the linked tutorial described below, reading the Painter  User Guides, Help menu PDF files, and Help menu Index, and/or using other tutorials related to Layers (Floaters/Transparent Layers), should get you to the point of understanding them in the quickest manner, as long as you put what you've read to practice fairly often until it all sinks in.

A related tutorial suitable for both
Painter 6 and Painter 5/5.5 users

There's another very simple tutorial on my site that should help with some aspects
of using Layers and Layer Visibility Masks, also referred to as Masks
(Painter 5/5.5: Transparent Layers and Transparent Layer Visibility Masks, also referred to as Masks, in addition to giving you some information that applies also to Floaters and Floater Visibility Masks). 

"Erasing" on a Transparent Layer - (Transparent Layer Masks)

It's also found near the top of the list of tutorials on the PixelAlley main Tutorials section page (along with a lot of other tutorials that were written for Painter 5/5.5 and Painter 6 (many of these include translations for Painter 5/5.5).

NOTE: I should add, because it isn't explained in that tutorial, Masks that correspond to Layers (Masks that correspond to Floaters/Transparent Layers) are Visibility Masks. In other words, when you paint on them with white to increase the transparent areas of the corresponding Layer (Floater/Transparent Layer), what you're doing is making those painted areas invisible. They remain even though you can't see them and can be restored to visibility by painting those areas of the Mask with black.

Once you get these things under your belt, and practice them for a while, you'll be a long way toward understanding Layers (Floaters/Transparent Layers) and their corresponding Masks, and able to use them with ease and pleasure. You'll be amazed at what you can do with them and how useful they are for all kinds of projects done in Painter. It's not really hard to learn. It just takes time and practice.
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