If you're looking for a coven go to the groups tab and scroll through the different covens. Read what each one has to offer, perhaps talk to some of the members and see which you want to join- if any.
As for the picture. Click your profile tab. Then click edit. The first thing that pops up is an edit photo area. Browse and find a photo that matches the criteria. Keep in mind it can take some time to upload and be visible.