I'd lay it flat, spray it as lightly as possible with water to get most of the wrinkles out. Then wet down any spots that aren't cooperating more heavily with water. Blot up the excess water with a towel and let it air dry.
If a few of the wrinkles STILL don't come out, then re-spray just those areas with water and steam press with a press cloth on top and a bath towel underneath until the wrinkles are gone, then dry press until all the water is gone or air dry. Both the press cloth and the towel underneath should help prevent the ironed-look with seams showing through on the top.
-Christine