When I unzip and try to open a file like Pedro's aircraft I don't get the material/textures on the aircraft. What files do I need to move or change?

Are you talking about Pedro Caparros? All his models claim to be in .obj and Poser not .3ds format. Can you provide a link to which of his many aircraft models is giving you problems?

Yes, Caparros, same problem with .obj files.

Did Pedro include any .mtl files with the .obj files? The .mtl files tell any software that imports .obj file not only where the map files are but also what color the materials are. If no .mtl file is included then you have to define the colors yourself and test any included image maps to see if they are the ones.

What program are you using?

Anim8or             

It's been awhile since I used Anim8or but I think that it ignores materials when importing an .obj file. I'll have to check on that, though, because I'm not sure.