Warez = This is generally commercial software that has been pirated and/or 'cracked' to avoid having to pay to use it.
Keygen = Often used in conjunction with warez. This is a program that generates a keycode, serial, or registration number to activate a commercial program that was not paid for.
Avatar = See the pic of Leisure Suit Larry beneath my nickname on the left hand side? That's an avatar. Just a small picture used to identify yourself. If you haven't been granted permission to upload and use one by the time you've reached 100 posts, private message Number Six (forum admin) and request it.