forgot passcode how can to connect to itunes

Your question isn't clear. If your phone is disabled from entering too many wrong passcodes, you need to connect it to a computer and restore using iTunes. You can also log into the iCloud account associated with that iPhone and wipe it from there. It will put it back to original factory settings.

Force the phone into recovery mode, as described here, & restore it:

http://support.apple.com/kb/ht1808

This will remove the passcode.