Hello and welcome to the forums...
In order to be able to posts pictures and have an avatar, you first need to become a full member because as of right now you are considered a new member. New members are restricted to start new threads, post pictures, links, have an avatar or change one, sending private messages to other members. In order to become a full member, you will need to have 25 points, 15 posts and an account older than 24 hours.
A link with a list of badges that gives out points. There is a page that explains what each badge is but it's broken for the time being.
And this link is a tutorial on how to use the site..
A link for a thread for New Members to introduce themselves to the community.
I would suggest for all new members to go and read the rules of the site before posting...
A link to Forums Etiquette, Warning/Banning Process and the Forum Rules...
For any New members who what to get their post/point count up, the best thing that I would advise you to do is to find threads that may interest you and join in on them or go to the Off Topic section and join in on some of the word/story games over there. The posts made over in the forum section will go towards your post count whereas the posts made on your wall and the Activity Feed doesn't go towards the total post count. The only thing that you will get if you should make any post over on your wall or Activity Feed will be any Insightfuls, Likes or Awesomes as they will go towards your total points count. Hopefully creating your posts on other threads will also increase your points...
And for anyone who may have any issues with either TS3 or TS4, these are links for New Members to post their issues in.
Sims 3 issues
Sims 4 issues