Here and here is some free packs with pretty cool stuff so if u dont have time to make your own, go ahead :)
Now go into your dashboard and click add a gadget. Then hit html gadget...
here is sample of my add. first line is for your URL that you want that button to link to. Second line is for the url of the image you want. Be sure u replace just red script !!!
<a href="http://noonjewellery.blogspot.com/" target="_blank"><img