Just remove the asterisks. To get the URL right click the mouse over the picture, and click on properties. There will be a link there under "Address (URL)". To get a banner you can request a banner in the Graphics Showroom forum.
if you mean from your computer harddrive, I dont think you can do that, so upload the image on ImageShack or Photobucket, then copy the URL for forums (1) they give you, and paste it in your sig, then highlight the URL from the pic and click on insert image to get the image tags around it. Preview siggy and it should be there.
I've fixed your sig, seeing as you'd only managed to post the thumbnail view. I did, however, have to remove the other Orton pic as it was making your signature break the rules (and it wasn't as good as the new banner).