Firstly, I dont understand why you have 3 files.The model, skeleton, and animation/s can all be contained and exported from a single gmax file.
Your skeleton has not imported correctly.All the bones are irregular sizes and just bunched at the very center of the scene (0.0.0).Import the UN Ranger model along with the skeleton into Gmax, then delete the model, and merge your star wars trooper model with the scene (file--->merge).
Try these tutes if you are still stuck with stuff.
Inftute
Frankenstein