Hey Man. Here is what you need to edit tracks (it's not easy, though)
1. De2 Editor (available in downloads)
2. Microsoft Excel
3. TexDraw (available in downloads...this is what you paint the textures with)
4. Rhino 3d (this is optional but is a must have if you want to see a 3d model of the track you are editing to save hours of time. We can get you a link to this if interested.)
5. Macro's for Microsoft Excel (this is optional and there is a guide in the downloads section to explain how to make tracks in Rhino 3d without using these macros)
Hopefully this will get you started, if you have more questions just ask.