I am using CS4 and can't figure something out that I think should be simple.  I purchased a set of textures that came with two sets.  One is marked alpha; the other "color".  The alphas are masks, right?  So how do I apply them to remove the background on the images?  HELP!!  I'm going NUTS here!

I’m not familiar with CS4 but the alpha file should be the same size as its color counterpart... that is 640 x 480, 1024 x 768 or whatever size. Also, the alpha file is usually a simple black & white image or it can also have varying shades of gray.

This being the case open both files in Photoshop. Press “V” to activate the move tool. Select the alpha file and while holding down the Shift key drag it onto the color image and release. Holding the shift key down will center the incoming image over the other. You will notice that there is now a new layer containing your alpha image over the original color file in the layers palette.

Turn off the visibility of the lower (color) layer by clicking the little eye icon in the left column of the layer. Make sure the alpha layer is visible and is highlighted and click on the channel palette tab.

Assuming that the file is RGB you should see the combined RGB channel on top followed by the individual color channels underneath as R, G, B layers. They should all appear to be similar (your alpha image). You can drag anyone of the channel layers (R, G, or B) to the create new channel icon at the bottom of the palette which looks like a little sheet of paper right next to the little trashcan icon (delete). This will now create a replica of your alpha image on a new channel called alpha 1.

Back in the layers palette you can now drag the alpha layer to the delete icon at the bottom since you already have it as a channel. Or you may decide you would like to keep it there for keep sake but disable its visibility.

You are now ready to use your alpha channel. You will find that clicking on either the alpha layer or the alpha channel a selection will be made in accordance to the white of the image. This allows you to subtract that area from the color layer or you can work within only the selected area and do whatever you need do to the color layer. You can also reverse the selection by holding down Shift + Ctrl + I.

This is a quick and dirty tut. There is much you can do but that would be a whole other tut.

OK, I got to the last paragraph..lol. I've located the alpha channel that I dragged onto the image, but now how to I use it to delete the background?? Thanks in advance, and sorry if I sound REALLY dim!!

Sorry...Ctrl + click on the alpha channel to make the selection.

I've got the "marching ants" and the background now looks red...now what?

If the marching ants are around the background you can delete the background by simply pressing the delete key but I suggest you make a backup copy first in case you need the file in the future.

If the marching ants are not around the background then shift + ctrl+ I will reverse the selection.

I'm trying to make the background trans.

Ha!  Got it.  I needed to make a layer from the background before it would delete.  I could KISS you!!  THANK YOU THANK YOU THANK YOU!!!!!!!

LOL...you can rub my kitten's belly instead!

Yes, putting a background under the layer would show through.