From your profile page, click "annotated games." Then on the game list that comes up, click on "annotate" for the game you want to export. This will bring up a new window, and at the bottom there is a link for "Export PGN." This should do it.
[And just so other readers know, these are directions for using another chess site, and are meaningless here. But in case there are any chess.com staff reading this, remember that he wants to move his created content away from them and put it over here.]
I have quite a few games i entered and annotated using the gameknot chess tools, but once output they are all in java...is there an easy way to convert and include them in chess.com (without having the original pgn handy...as i also want the comments for each move