[Mazin]

Lol, Pete wants you to look up something else that's kind of related to sub-object materials.

I think what you're trying to do is put certain materials on certain faces, right?
Every face on your object has a number called the Material ID. You assign different materials to different IDs. So, if you have a simple building, the walls could be set to ID 1, the windows could be ID 2, and the roof could be ID 3. You set them by selecting the polygons and finding the set material ID box somewhere in Editable Poly.

In the Material Editor, you need to make a Multi/Sub-Object material. When you do, you'll see a list of ten different little materials inside it, each with a number next to it - its Material ID. To assign materials to the house for example, you could set the number of sub materials to 3, set the material #1 to a brick texture, set material #2 to a glass texture, and set material #3 to a shingle texture.

HTH.