placing logo(signature) over existing background

From: Bill Pruitt


I want to put my signature logo(from photo taken with my dig. camera) and insert as a photo image on my web page. So first I want to make it all transparent so you can see "through" the spaces between the letters and eliminate the original background so ONLY the letters are visible and it can be placed on the background. Is the eraser tool used for this? Thank you very much.