Is mobile network turned on? Are you in range?
You should not have had to do anything. When the service is activated on your account and the service books pushed, it should all just work. Have you been able to setup an email address in BIS? Does the native BlackBerry browser work?
You might try resending service books. See How do I resend my service books? - BlackBerryFAQ
After that, if no go, then I would call your service provider again and have them double check you account and make sure everything is configured correctly on their end.