It also depends on whether or not you were naturally waking up anyway. It may be that you became lucid in the last few stages of REM in which case there isn't that much you can do, other than lay very still and concentrate on re-entering the dream.
I agree with the previous post - check out the links to the tutorials you may find something that works perfectly for you.
Good Luck!!

p.s. Congratulaions on your first Lucid Dream