Please help me.. I could not find any videos or anything about this. i have figured out how to pla custom maps, just not custom skins and all the other extra custom goodies people have made.

Usually the author would have some kind of instructions to tell you how to install them. If it a custom skin for multiplayer (or singleplayer for that matter) you need to override the original file in the VPK otherwise it will not work.

Try looking for better instructions elsewhere.