I thought FEN strings corresponded to a single position...though I'm not positive.
When I want to post a game, what I do is go to the game in my archive, select all the moves, copy it. Then go to the game inserter and paste it in the PGN file location. And there you go. Hope this helps.
How do I find the "FEN string"?
I keep copying it from the original game (which was a live game), but it says that it is invalid.
Suggestions?