you cant get a free, but trials.
google : photoshop trail downlaod or paintshop pro 9(or 10) download.
Skinning in gimp?
erm...hard to say, i dont use it much. Just open a skin (tga format) edit it.
use the eraser tool to great alpha effects on the skin(transpareny)
sorry, thats all i cant since since gimp isnt used alot.