Saving using channels

I was trying to save an image using one of the channels, using photoshop CS, but it saved as the original image. What i did was go to the channels tab and checked the channel that i wanted, but it didn't show up in the preview window, only the main window. What do i do to save using one of the channels. Any help is appreciated.

If I understand, you want to save the channel itself as the image. In that case, go to the channels palette, select the desired channel, Ctrl+A to select all, Ctrl+C to copy, then go back to the layers palette and paste into a new layer. Now you can save this; it will look like the channel, but is actually the image.