Well the gmail thing was kind of an example of an available service, probably not quite the right server and I'm sorry if it confused you. But, one way to send an sms is to fire up the app responsible for sending messages. You send the OS the information in an intent and it does the work of starting the app. But you have to tell the app to send. You can also just send one and manage some of the details yourself. Here's a pretty good code example of how to send and receive sms messages.http://pankajchunchun.wordpress.com/201 ... n-android/
I am not very familiar with mms. It's rather new to Android and I have read a couple of things about doing it but have not done it. I have done sms some.
If you are new to Android, the nuts and bolts of sending and receiving messages is probably trivial compared to getting input from the user, storing things, using the contacts list, coming up with graphics and showing it all on the display. Its all about the UI and I may be able to help you with that.
Hope this helps.