Installing new skins.
This is harder on you computer-illiterate types. In general, you download a skin you want to use, find a skin you don't want to use that's in the game, (let's say it is the third skin of the Thing, stored in the file 0503.igb residing in your game's ACTORS folder) BACK IT UP, unpack the downloaded file to a comfortable temporary directory, rename it to 0503.igb and copy the result to your game's ACTORS folder, agreeing to overwrite the existing one. Ta-dah!
BUT adding new skin slots is a whole different ball game which would, for a computer-illiterate, require a FAQ longer than I care to write in one sitting. So, either quit on the idea altogether or wait till our resident experimentators finish their project on making a mod of it. So there.
(tut by Noelemahc) the .igb is just the type of file you will only need to replace the 0503 by overwrite of the old one, if your actors folder is empty you have messed it up so you'll have to reinstall the game than do whats in this post good luck and have fun.its simple copy and paste.