Blackberry help! I just bought a blackberry curve 8320 and i need help getting on the internet. im using wi-fi?

im using wi-fi for internet and its connected to my router but when i use the browser it keeps saying unable to connect to the internet. AIM wont work either and since i have unlimited messaging i want to use it (but it keeps saying service not enabled for this handheld).. Are we suppose to use blackberry enterprise as our browser? or do we have to pay more for that (data plan)..if we r suppose to use that on wifi how do we turn it on..cause i think mine is turned off