lol, well you should give the following tutorial a go...
http://forums.halomods.com/viewtopic.php?t=56916
It shows you how to PMI a wraith, C dropship and pelican. Just follow the instructions to import the wraith. When it's in the map, it's already destroyable (and drivable, sweet

)
To test out the gun, simply fire at the wraith through the scenery you modded (be it a tree or what ever).
If the wraith begins to smoke, way hey, it's working. If it blows up, well it still works except you got yourself a cool firework show
