Currently Being ModeratedNov 12, 2012 10:26 PM (in response to quackquack113)
Welcome to the Apple Support Communities
Open Messages > Preferences > Accounts, select the Apple ID, turn on the phone number and deselect the email
Currently Being ModeratedNov 13, 2012 2:54 AM (in response to quackquack113)
At the bottom of that window under Accounts there is a a menu "Start New Conversations From". You can select your number there while leaving the number and email address selected above for receiving messages.