Create a small image with your initials with a box around them, as I have done below. Save that as a GIF file, then convert that to a transparent GIF using Microsoft Photo Editor or any suitable image processing program. When you have created both images, put them on a Web page like the one below. Print it out to turn in, and place it on your Web site with a link on the assignments page.
My initials with a blue background:
My initials with a transparent background: