Welcome to the forums! You need to have 25points and 15 posts before you can become a full member and can then change your profile picture , post pictures, have a signature, start new threads, edit posts , post links that show up correctly, and have quotes appear in grey boxes ,This thread explains about it.
Happy simming! :)
When you are a full member and can start new threads, you could start a new thread in the Sims 4 Sims and Modelling section of the forums and post your sims there .