Transparency in images is different on the Web than in Photoshop.

To get an image that is somewhat see-thru, you must turn it from an 87agif to an 89agif. This means little to you other than you need to go to MenuBar->File->Export->Gif89a to save your file out as a transparent gif. A dialog box then comes up and asks you to click with the eyedropper into the area of the image you want to be see-thru. This turns the area greyish. Then save out your image. It is now an 89agif! Wow, who cares... However, now when you use this image in your html pages you will be able to see-thru the color that you designated as transparent.