You need to wait until you are a full member in order to add an avatar. If you post an average of 1 post per day, post at least 1 post every two weeks and have at least 120 posts then you will become a full member in approximately 4 months.
Yes. The forum have added this before there were hacking into the forum years ago, and avatar was disabled here for a long time. It then re-enable it since some point in March/April, but require Full Member rank to upload an avatar (to prevent attacks).
If you post here everyday, you'll got to 126 activity after 8th December 1:06:40 PM UTC, with extra 1h waiting for activity update.