Oh hey, I just realized you asked me a question. Sorry, I got caught up in the monthly challenge. As far as making a sea it's really just a matter of creating a new layer for the Sea, then selecting your land area and then growing/shrinking things. to adjust from light to dark. For the texture of the ocean use a fill of noise or plasma or something. Oh and be sure to use the 'feathering' option so you don't end up with a hard line where the colors change.