HT1296 how apple define sync vs overwrite vs merge

I have a new Macbook Pro, and an iPhone 4 that contains my contacts saved from the last computer i had, a crashed PC. I dont want to send my contacts to the cloud, but want to download them into my macbook pro and be able to have the two devices update each other when connected. I just created a backup for my phone on my new macbook using itunes,my itunes account id, and a usb cable, but I expected the contacts to move over in that action, and they did not. All my software is up to date, but I can't figure out if my macbook contacts, which is almost blank, will overwrite my  phone if I just perform a usb sync again.