As WHICH image? User page header (appears across the top of your user-page)? Personal icon (appears as your icon when you leave reviews and on the page of your Flash submissions)? Forum signature image (appears beneath all of your forum posts)? That will determine image size and file-format you're going to want to save in. Otherwise, it is all a matter of using image-editing software to create what you want, save it off, and upload it.

I can't upload it for you. Nor am I going to reproduce Photoshop in Flash... well... not without some major monetary compensation.