When you first run the program, you will be prompted to enter the name by which you would like to be known to other players. Enter a name a press OK. (You may change your name later in your Preferences settings.)
Next, you will be asked to enter a password. you Enter a password and press OK. The password is used to protect your identtfy during a game. It is used to determine who can see invisible or masked counters, private windows, etc. You can pretend to be another person by changing your password to theirs in the Preferences setting. Assuming, of course, that you know it.
In the VASSAL Controls window, set your Preferences by going to File - Edit Preferences.
Name
Whatever you enter in the Name field is the name that other people will see in the Chat area of VASSAL. Use a nickname or put your full name. Its up to you.
Personal Info
Enter any personal info which you would like to make available to other VASL users.
You may read another player's profile by right-clicking on their name in the Server window and selecting Show Profile.
Use Arrow Keys to Scroll
Checking this preference allows you to use the arow keys on your keyboard to scroll around the map window when you have no counters selected. If this box is not selected, the number keypad will scroll the map window.
Chat Window Font
Specifies the font and font size used in the VASSAL Controls window.
Opponents can unmask my pieces
A "masked" piece is a piece that is visible to all players, but whose details are only visible to the owning player. If enabled in the module, this preferences setting determines whether players other than yourself can manipulate pieces while they are masked.
Center on Opponent's Move
The Center on Opponent's Move checkbox will automatically center the map on a unit that is being moved, whether connected to the server or reading a logfile.
Auto-Report Moves
If enabled in the module, the Auto-report moves checkbox will echo to the chat window a description of any pieces that are moved with themouse. For example, if you drag a unit named "3rd Army Division" from hex E5 to E4, then VASSAL will echo * 3rd Army Division moves E5 -> E4 *. VASSAL will use the piece names and mapgrid labeling specified in the module configuration.
Marked Moved Pieces
A VASSAL module can configure certain units to be automatically marked when they are moved with the mouse in a map window. The Mark Moved Pieces checkbox turns on and off this automatic marking of units as they move. Click Mark Unmoved at the top of the VASSAL Map window to clear the "Moved" status of all units.
Use CTRL-space to view stack details
If enabled, the mouse-over stack viewer will display the contents of a stack when you rest your mouse over it. Alternatively, this setting causes it to display the contents when you place the mouse over a stack and hit CTRL-space.
Other module components may have their own tabs in the Preferences window (e.g. the "Thread" tab for Line-of-Sight related preferences).