Menu above: Actions > Show my adjourned games. A window opens with a list of your adjourned(stored) games.
Click on a game to 'View' it. Right click on a game in the list and choose 'Examine' if you to try out different moves.
Menu above: Game > Resume
This will send a 'match' request to all opponents for which you have an adjourned game, and who are not currently playing a game, and not in a tournament. If one of them accepts the match request, the adjourned game will begin and you can finish it with your opponent.
(Old versions of BlitzIn will have to type 'resume' on Main Console.)
For more information read "help resume".