If you have teenagers you know all about texting.
I had never sent a text in my life into my oldest child got a cell phone. All they do is text. If this tutorial Aaron from Zollotech teaches you how to use your iPhone to send and receive text messages.
If you have an iPhone 4 I would suggest you take a look at a free app called Dragon Dictation. Dragon Dictation allows you to speak into your phone to send text and email messages. On a personal note, I find that I am most likely to send a text message if I can speak what I want to write. I just find it faster and more convenient. The iPhone 5 has a dictation tool built into the phones software.
Texting with Your iPhone from Zollotech: