can anyone show me how to make edward cullen's wristband?

he always wears it. it is mostly black, and has the "cullen crest" on it. if anyone could show me how to make it, please do. there is a picture here, just in case.

The bracelet itself is just a strap of black leather with two holes in each end and a leather thong to tie it together. You should be able to find the right thickness of leather, black dye and a hole punch at any decent craft/hobby store or Tandy/Leather Factory, possibly even in kit form or pre-dyed black.
The tougher part is the crest. Try Hot Topic or Spencer Gifts for a replica medallion in pendant or keychain form (or even a full wristband replica for that matter). If you have to make the crest yourself, I'd recommend polymer clay such as Sculpey ot Fimo. It's easy to sculpt,  and very durable after you bake it in the oven. Use a color that's as silvery as you can find, to help reduce visible dings and scratches in the paint. Paint with a high quality metallic silver, and add detail with black (or silver with black mixed in, unless you're going for a high-contrast look).
If you want to make a metal medallion, that's outside the scope of this Answer forum. Google "sand casting" or "lost wax casting" for a better idea of what would be involved in that. It's not all that difficult, but it's quite an investment in tools and supplies to make one bracelet.
Once you have a medallion you like, rough up the back of it with sandpaper and glue it to your wristband with a strong glue like E-6000 or Amazing Goop.