how do you pair a iphone to a iphone

You don't. This has never been a feature of iphone/ipod/ipad.

Bluetooth is supported for stereo headsets/speakers, handsfree telephone headsets/devices, some keyboards, some peer-to-peer apps from the app store, and internet tethering where provided by the carrier.

Other than this it will not connect to other phones/computers/devices.

You don't. That's never been a supported function of the iPhone.