how do i sync my new computer to my iphone using bluetooth?

You may need to provide more information on what you mean by "sync." If you are referring to an iTunes sync, that cannot be done via Bluetooth. An iPhone is not designed to pair with a computer via Bluetooth but it does have several features that require Bluetooth to be turned on for both the computer and the iPhone. More information at: Bluetooth: Why can't I pair my iPhone or iPad with another iOS device or with my computer?