Making the skins stick

[LordofDemons]

I have Kyles skin, and I have the skin I want to change it too which is Darth Maul, I also have jan's skin and the skin I want to change it too which is her in this red fighter outfit. I have the kyle player file open with the jpegs and the model_default file and I have the file open of the skins I want to make them have. I cahnge the skins in the original kyle folder to the new skins, I replace the jpeg with the new jpeg, when I try to play the game, it's a no go. I rename the file in the original kyle folder to the name of the new skins, no go. the original file is not set to read-only, what can I do to change the files in the game Kyle folder to the new skins of Darth Maul and make it stick in game? (BTW I'm only using single player, and the skins I'm getting are for single player)