In order to start a new game it will be necessary for you to create a Game Room for you and your opponent to play. In the Server window. type the name you wish your room to have into the "New Game" field and press Enter on your keyboard. You should now be the sole occupant of that room. If you enter the same name as a currently-ongoing scenario, you will join that room instead.
While connected to a scenario chat room, all moves are broadcast to all players and maps are updated automatically. You can save and restore the game to files on your local machine. If your map and your opponent's map appear to differ (e.g. due to lost moves during a broken connection), synchronizing by right clicking on your opponent's name and selecting "Synchronize" will update your map to coincide with your opponent's.
To begin a new game (as opposed to continuing a saved game) choose File - New Game in the VASSAL controls window. You may be prompted to choose boards as explained below. To save the game to resume later, choosing File - Save Game. To load a saved game, choose File - Load Game and select the save game file. Some modules are packaged with savefiles of common scenarios.
VASSAL supports games with geomorphic boards. Not all of the
boards that come with a game may be necessary to play a particular
scenario. If prompted with the "Choose Boards" dialog, select
the boards you need for the scenario from the drop down list.
To add another board, select whether it will be placed
horizontally (Add Row) or vertically (Add Column).
If the map needs to be reversed (rotated), check the Reverse
checkbox. If you made a mistake setting up the maps. you can
click the Clear button, to reset the window so you can
start again.