I wanted to update my avatar with my own image as a new user and couldn't. So I did a search and found a couple of threads where the answer was you have to earn 25 points and the another answer was you have to post at least 10 replies. Does the 10 posts give me 25 points? Or were there two different rules in the past?

I guess what I want to know is, how can I add my own avatar? Where can I read the rules for getting more functionality (awards, promotions?), if there are more of them?