advice on 600 gallon tank start up

Hello to all! This is my first post to please excuse my newbie ways. I am thinking of starting my first saltwater tank. I was originally making a 600 gallon concrete tank/pond for an aquaponic system but now that the tank is almost done I am having second thoughts. I live very close to the ocean so I can scavenge all types of fish and live rocks, however my knowledge of saltwater tanks is zero. Ive tried looking for simple starter guides and what Ive come up with is you need to start with live rocks which keeps ammonia levels down...i think. Then you can add fish and maintain the salt level. What Im really looking for is a simple, easy to understand guide on how to deal with moving live rock and fish and basically caring for the whole system. Any help or points in the right direction would be awesome. Thanks.