Ok, so how do I take the Mara Jade model I D/Led and use her in SP?

Usually instructions are included in the readme file (or you can contact the author).

However if this was made specifically for JA (and not a JK2 model) you should be able to just drop it in your /base folder and start up the game.

If done correctly it should appear in the list of models you can select. If it just replaces Kyle (in which case it's definately a JK2 model) then you'll see it by spawning Kyle Katarn in SP (npc spawn kyle).

Well, its not an SP model, its a MP model. Its the GLM Mara Jade model from JK2. I thouhgt i read a post somewhere, that if it has a NPC/Bot file it can be used as a playable char in SP???

Check out the tutorial here. (http://map-review.com/index.php?page=tutorial_view&id=7) It takes some editing, but it is possible.