Currently Being ModeratedNov 13, 2012 2:30 PM (in response to mlzeit)
While that might have seemed to be a rather flip reply, it's in essence the only answer anyone can give. There's no way to monitor SMS or MMS messages your daughter sends from her own iPhone. Only the cell carrier could do that (if the carrier does record the actual content of the message) and I doubt any carrier would give you a log without a court order. You may be able to see how many messages she's sending and the phone number to which the message was sent on your phone bill, but that depends on the carrier.
For messages sent via iMessage, you could sign into Messages using her Apple ID and password. You'd then see all the messages she sends and receives via that service.