textures

hi, sorry for this stupid question.
i downloaded a bunch of textures. but how do i use these? i just dont know how to start making an icon with textures.
how do you make icons?
do you use the texture as the "base" and put the other pic on it or the other way, the pic is the base and you put the texture on the pic?
could someone give me hints (or tutorials) how to start making icons with textures.
thanks in advance