Krazyj. To find out how it's done check out a few threads in the Aircraft Repainting forum.

Editing the textures is not difficult once you understand the principle. The first thing you need is a good basic knowledge of ordinary graphics editing software & image formats. It's also an art & a little artistic flair would help. Some people are more gifted in this respect than others. Although I can explain the technical side I will never be any good at it myself.

You might like to read this tute which explains what you need & the basics. http://www.calclassic.com/repaint.htm
There are other tutes & each will vary in some way. As with anything else there is usually more than one way of doing something. We all have own favourite methods.

PS. Most tutes will recommend Paint Shop Pro or Adobe Photoshop as the graphics editor. These are both commercial products & expensive. Don't let this put you off trying . There are several excellent freeware alternatives. If you have nothing better you can start off with M$ Paint which is bundled with all versions of Windows.