how do i enter a phone my son locked and he doesnt remember his passcode
You will have to back it up and restore it on the last computer it was synced with (see bottom of this article: http://support.apple.com/kb/HT1212). If that computer isn't available, you'll have to restore it from recovery mode (see http://support.apple.com/kb/ht1808).
Do as the manual says to do and restore the iphone.
Retrieving data ...