Most Helpful Girl
There is no premium membership on this site.
When you reach level 2, you can post pictures. You earn Xper points and reach level 2 by being active on the site.
On your own questions and takes you can either upload your own photos, or copy & paste the link to a photo. When you post opinions, you'll have to paste the photo's link.
Photos will not show up in question updates or opinion comments.
The FAQ explains how to add pictures to your posts and what the limits are and such: http://www.girlsaskguys.com/faq/posts#1761