First off,
- Head over to :
http://www.fpsbanana.com/skins/games/2 - Choose the weapon you wish to change (The list down the side)
- Now choose the new skin
- Once downloaded, open up the Rar.
- Go into your Steam Directory > "UserName" > Counterstrike Source > CSSTRIKE
- Extract all the included folders into CSSTRIKE and overwrite all
- Open CS and choose the weapon you just skinned
- Enjoy the new gun + sounds!!