You should find the "Edit Avatar" section just below the "Edit Signature" section and just above the "Gender" sections, [@Hazardous Siren]. The site does not have available avatars so you will need upload one using the button attached, with the image being limited to the following:

[quote=Mahz][list][*][b]Max dimensions:[/b] 150px width, 200px height
[*]Images larger than these dimensions will be resized
[*]Animated GIFs often break when resized by the system, so you may want to resize them yourself before uploading[/list][/quote]
On the note about roleplaying topics, I suppose then that comes down to how much you enjoy writing in terms of amount. The Free section tends to be a few sentences and at most a paragraph, Casual is a paragraph or two, and Advanced is several and more. Generally speaking, high fantasy is quite common, much more so that low fantasy as sword and sorcery and the like, as well as fandom based fantasy.