How to make my iphone work for straight talk?

I have a iphone 4 and i would like it too be changed from At&t to straight talk.
Help?

You can't… IPhones aren't made to do that, unfortunately.

Just unlock you iphone get the code from ebay for less than 5 dollar and then take it to straight talk
http://www.ebay.com/itm/Factory-Unlock-Code-Service-for-AT-T-ATT-USA-Apple-iPhone-3GS-4G-4S-5-UNLOCKED-/261143299502?pt=LH_DefaultDomain_0&hash=item3ccd5a85ae

Just pop in the sim card and change the settings.
the directions are on the straightalk site.
it doesnt need to be unlocked

Buy an att based simcard from straight talk site, insert it into your iphone, and you are good to go.