If you just want to see some colors on your model, just use the hypershade and your JPEG texture files. For advance texturing, you need photshop, paint shop pro and wide array of texture maps. You also need to learn how to use Plannar mapping under Edit Polygons, and the Texture view. It is a very long process, so I recommend to look for a book that explain these sytems well.
2d and 3d are brothers, both need to be mastered.