Is there an Idiot's Guide to creating screens? 

I'm at the point where I know what I want to do for my main screen.

There are videos.

Bottom of the page for using Screen4.
http://www.machsupport.com/videos.php

If you want to use Machscreen, Klaus has some video's on his site.
http://www.kd-dietz.com/klausphp/index_eng.htm

There's also some info in the Mach2 customization guide. http://www.machsupport.com/docs/Mach2_6.11_Custom.pdf

Making a screenset is fairly straightforward for basic ones and you should fall into it fairly quickly just by messing around in one of the designers. Personally I dont use a background image that is boxed for different panels, this makes it much easier and quicker to make a screen up as you can pull the controls about the screen and place them where you want. If you use a background image with defined area like on the standard screen you will really have to plan what you want and where you want them so you can make your background image up.

I use Screen4 and the only thing you have to be careful about is once you have selected the function on the left then placed it on the screen you then press the None Icon or you may inadvertently keep adding DROs or whatever each time you click.
Hood