for the BB curve 8900 or any handset in general, there are two main ways for accessing the data, either through a wireless network i.e. wifi or the home network which the service provider i.e the carrier who provides you with the signal service.
in order to get the internet access through the Wifi, you need simply to make sure the wifi on your 8900 is turned on and it will start searching for the wifi coverage in the place where you are present and you can connect on the spot once you have the password for the wifi connection.
In order to get a connection over the home network
1) the BB has to be provisioned in the sense of the signal bar should show EDGE or GPRS or 3 G with the BB symbol beside it on the top right corner
2) You need to register your phone on the BB server from your end by going to
Advanced System Settings
Host Routing Table
Press the menu key and register now
It will tell you registration message sent
Just take the battery out of the phone and put it back in after 30 secs max
it will b ready 2 go 4 u :)