TGAs are used to have textures
(colours) on models. Note that in glest, you can use either TGA's or Bitmaps
(BMP). TGA stands for Targa, but that's unimportant. I'm going to assume you've
already done the model section of this guide.
When saving TGA's, save them as .tga, not as .TGA, as linux users would have to
change that to lowercase to get it to work.
There are three main TGA
editors: the GIMP, (GNU Image Manipulation Program) Paint.NET, and Photoshop.
Between these, the GIMP and Paint.NET are free. The GIMP is great, but very hard
to learn, so not for beginers. I don't know why, but I just don't like the GIMP.
I still haven't gotten around to reading the manual. (653 pages, sheesh!) So I
use Paint.Net. Unless you already have some experience with the GIMP, I strongly
recommend Paint.NET. Paint.NET is a very good software and can do many of the
things that the GIMP can do much easier. (Mostly buttons on the main taskbar,
though there is hotkeys and all too!) Lastly, Paint.NET can do pretty much
everything you need for getting TGAs ready for glest.

This
is the main screen of Paint.NET. Nice and simple layout. Load the TGA.

Here's
the TGA for the swordman. As you can see, we see the sword in the top corner,
with the hilt next to it, and the shield (front and back) And of course, we
can't miss the main body, which is divided in half. The head and the back of the
head is down beside and inbetween the body parts.
In Paint.NET, we just
edit it simular to how we would for MS Paint. Notice the checkerboard patterns
in some parts. That is alpha. On double sided models (default) the alpha becomes
team colour (the colour that adjusts per team, red is team 1, blue is team 2 and
so on...) On single sided models, alpha becomes transparency. In Paint.NET,
alpha is applied via the eraser, and if you set the primary colour to less
alpha, the eraser will only erase a little and not all, leaving the base colours
lightened with alpha. To get realistic textures for cloth and stuff, usually one
must use textures, which may be downloaded from the web (check the copyright for
the images) or just grab a digital cam and take them yourself. You can modify
them to be more suitable, and of course, you'd have to resize them and crop them
to fit the unit. Making good TGAs is not as simple as colouring with a solid
colour (this causes the model to look simple)
Much of the time, you will
be with UV maps exported from blender, so make sure you know what each piece is,
and it's orientation!
For help with Paint.NET, go to http://www.getpaint.net/doc/latest/index.html