Adding textures to weapon models?

[Yunker1993]

So i have models for multiple weapons but i cannot for the life of me learn gimp/nifskope/3dsmax. I want too apply the textures to the Aliens Pulse rifle and an M1 Garand model, create the mod with attachements.....or not idk, and add it to levelled lists. If theres a guide for noobs please shoot me a message directly if you want to as well.