bought a blackberry pearl that is locked to rogers, do i have to unlock the

You have to unlock your blackberry only if you want to use the other country network provider in your mobile. Unlocking is the process of releasing the network lock..After this process you can use any network ..
It can be done through codes.I found an unlocking service for your Blackberry pearl at Onlinegsmunlock.com . You can use this and unlock your mobile easily.