Quick, Easy Graphics Job - Apply Transparent Background to Existing Image

I require someone to place an existing image onto a transparent background for use on web pages. The current image (an image of a person's signature - please note for security reasons the signature is not the real signature of the person) is on a standard background (currently coming through as off white) and simply needs changing to a transparent background so the image blends in perfectly with any web page. Please note I expect this file to blend in perfectly to any background so please don't bid if you don't have the experience or software to do a professional job. The file will be provided to the successful bidder.