I assume that your current carrier is GSM. It helps to know which one you have, so please update your profile with that information.
Is the device from your carrier? If so then you need to call them, activate the device and insert your current SIM. To use most data features such as email, BBM, Facebook, maps and any other RIM related services, you will need a specific BB data plan from your carrier.
If the device is not from your carrier, you will first need to unlock it if it isn't already, before you can use it.
Please see our FAQ for additional information. You should also download and read the 8800 user guide.