If you look around the forums for item packs, there is many marvellous ones I will post below. They will show you where to put them.
Once you have a few, go in-game and go to the second to last tab. You will see them there. Click on them once to add them, then again to remove. You can have either 5 or 6 (cannot remember)
Make certain you follow the creators instructions. If there is more then one .cgf files, go into them, copy one, then paste the copied into the other one. (confusing, I know)
My apologies for the confusing manor I wrote this, not on my computer.