On SR, btc is just a currency: many of us do not immediately change it back to our local money, but keep it stashed, either on SR, or in some other online site.  Takes a bit of research to figure it all out...my suggestion is to get on SR forums, and study up a bit, before doing anything else...all these sort of bitcoin questions have been discussed at length.  Again, SRforums have plenty of stickies and there are friendly members who will help out.  I wouldn't do any transactions on main site until going there.  But there have been ripoffs, of drug and bitcoin buyers, both, so study up a bit...it's considered part of 'paying your dues,'...best wishes...