Give your teen time to digest the rejection and see what he can come up with as a different path on his own. Be encouraging without being patronizing and offer your help - to visit other colleges, etc. - when he asks for it. Do not share this information with other people until your teen says it's okay, or allow him to tell family and friends - preferably when he is accepted to a college he wants to attend.
Parenting Teens: Getting Into College FAQ:

