Hi
Bennylava2,
Welcome!
OK, first thing, please add you car's details (year, trim etc.) to your signature. This makes it easier for us to help you, as the are some big variations over the entire model run of the E53.
Next, grab a coffee (or something stronger), sit down and have a read of this: -
BMW X5 Aftermarket Radio Installation | Crowz Nest
You won't have many questions after reading this (and the thread here on Xoutpost that is referenced).
For my money, I'd put in the Seicane unit that
Crowz used - along with the iBus items.