i cant get my blackberry curve on the internet without wifi :(?

[abzz47]

i have a blackberry curve but this one is a replacement becuase my other one broke. i pay on my contract for internet and on my other blackberry before it broke i could connect to the internet via gprs but i cant manage to do this on the new one. its the same model and everything. i can get onto the internet using wifi when im in my house but thts cuz i connected to our wireless at home. can someone please help me cuz i really dont know how to do it and im paying for a service that i cant work out how to get :s . thanks