Files not opening

So I just got hitfilm 3 express and I need to make a few scenes for a star wars film (deadline is before april 20, 2016) and I'm having trouble. Everyime i open a 3d model file, such as .3DS and .obj, it never shows up in the media thing. Several forums said that these files should be able to be opened, but none will. 

p.s.                     I'm running out of time very fast, someone please help me