I just got a new laptop ... How do i sync the music already on my iphone to itunes on my new laptop

The iPhone is not a storage device. The sync is one way - computer to iPhone. The exception is iTunes purchases. File>Devices>Transfer Purchases

You should copy everything from your old computer or your backup copy of your old computer to your new one.

If you don't have access to the old computer or a backup of the library see Recover your iTunes library from your iPod or iOS device.

tt2