Help with recieving and sending pictures on my blackberry?

Ok I have an 8800 Blackberry, for t-mobile and when my friends tell me they sent me picture messages I never get them and I tried sending a picture message on mine but then it said "No MMS Service Record, message cannot be sent. You will only be able to save draft." By the way, what does SMS and MMS mean? Oh, and I had an older style, like WAY old, phone and I had just switched the sim card from that model to the blackberry. The older model could send and recieve messages, so I'm guessing it's the phone itself or something?