hi there
i am new to bb world, and i just got 8900 as a gift.
i am wondering how to use the instant messaging.
i have added my friends pin code but they didn't receive my invitation, nor i received theirs.
what do i need to activate this service?

You and your friend must have a blackberry data plan to use the BB Messenger (PIN messaging). Contact your carrier on how to add a blackberry data plan. Note that you cannot use this with a generic data plan -- it must be a blackberry data plan.