Welcome to RS. Yes, you need to cycle the tank before stocking it with animals. The live rock will aid in getting your levels balanced. Most people toss a "deli" shrimp, just a raw dead shrimp in the tank and let it decompose to start the ammonia cycle. It should take about a month for the levels to settle out completely. When your ammonia and nitrites read zero you should be good to go. Just be sure to add fish and other animals slowly, not all at once.