I'm pretty new to this aswell, but from what I've seen so far, I think it's possible to trade Steem for Steem Dollars, same way you would trade other crypto currencies.
I'm not completely sure though, so I hope someone more knowlegeable will give you a good answer!
I thought that might be the case as well, but when I click on my options for STEEM I get the following
None of which seem to go to SD :(
It seems @chrisaiki is already helping you further along!
Quite so! And I am very grateful to him for taking the time :)