Hi, Madeleine -> This is Zacky. You can change your picture by going through these steps:
1. Go to "Settings"
2. Slide down to a place where it says "Change your Avatar"
3. Click the one available below
4. Click green button "Save"
What I meant by my first response to you: right now you cannot choose your own photo or your own picture to be uploaded apart from the ones offered by site. But we are working on it!! Thank you! Tell your friends about my site.