I have no service: THIS QUESTION IS ABOUT DATA AND MESSAGING

THIS QUESTION IS ABOUT DATA AND MESSAGING

I have th Pantech Link Go phone but I can't acess the web or AT&T Messenger. Everytime I try it says server not found. My friend also told me that if the 3G icon wasn't orange then the 3G wasn't working. Is there something wrong with my phone? Do I need to purchase a data plan for everythng to work properly? I just read that 3G had to be enabled how do I do that?