how do i apply textures to certain faces only??

I'm not exactly sure, but I'll concoct a quick tutorial for you, simply cause I have nothing better to do on a sunday.

You need to have a Multi/Sub object as your texture, which will be the texture for your entire BSP. This can be accomplished by clicking the 'Standard' button in the Material Editor, then clicking 'Multi/Sub-Object'. Click OK at the next dialog that pops up.

Your Material Editor window should have several sub materials shown below the sample materials.

Now, click on one of the materials, and name it to whatever you want. Then apply your material to the subobject. Do this repeatedly until all the materials you want are filled. Delete the excess materials.

Now you need to apply a material ID to the faces in Edit Mesh mode. You will need to select the faces, then scroll down in the modifier window a bit to find the option where you can assign the material ID.

Apply the Material ID according to the ID shown in the Material Editor. This will apply the material to the selected faces. Make sure you have "Show Result in Viewport" toggled.

Hope this was clear.

i know how to do this, but nice quick tutorial