Your question is a little vague. Are you asking if once you add live rock, if coral will just grow, then your answer is no. You may get a polyp or two of something that will start to grow but, if you want to create a reef tank, you will need to add coral piece by piece. I suggested reading the New to the Hobby forum prior to adding anything. There is a ton of info for beginners there.
Good Luck!!
pedro