Maybe this will help:
http://www.filefront.com/15736359/SM...eDarkWraith.7z
look at the files contained then open with the mission editor. There's a key file involved when making your own missions - the project file. You'll see it in the files I included.
Unzip to MODS folder - JSGME ready.
When you enable it, you'll find it under 'Historical Missions' labeled as 'Deck_Gun_Training'