HOW do I get this set up to PLAY already!?!?!?
Open VASSAL

This is the Module Library window. It will hold any modules you play in a list for easy access. Once you load this (and any other modules you discover), it'll stay in your library for ease and speed of game start up.

Open Module, Find X-Wing.vmod wherever you saved it.

VASSAL will start the game up, at this point, you can just Cancel the load, and close the game. We're going to add the extensions first.

Right-click on the X-Wing module and choose Add Extension.
Browse to the place you stored your files and choose one to add (we'll start with the 3'x3' map).

VASSAL will create a folder with the Module name_ext to hold all your extensions and will move the extensions into that folder.

(NOTE: In the past, I had a friend who did not have Administrator Access to his computer, and he was unable to load extensions because Windows would not allow VASSAL to create the extensions folder. If you run into this problem, you can either just create the folder yourself as seen above, or right-click the VASSAL icon and choose "Run as Administrator")

Note the little blue key to the left of the Module name now? this indicates sub-files (loaded extensions)
Click the blue key to see what's loaded.

continue to Add the rest of the extensions as above, and your Library window should look like this:

Now you're ready to fire it up and play the game with all extensions loaded, all X-Wing Booster packs available.