how can i join cellular data in iphone 4 from h2o service?

Morning pppfrom,

Thanks for using Apple Support Communities.

For more information on this, take a look at this article:

iOS: Troubleshooting Wi-Fi networks and connections

http://support.apple.com/kb/ts1398

iPhone: Troubleshooting a cellular data connection

http://support.apple.com/kb/ts3780

Best of luck,

Mario