Welcome aboard. Now starts the slew of questions whose answers will lead to more questions. How long has the tank been up? What sort of filter are you running? As far as for corals, what type of lights do you have?
In general, everything I've learned in my short time in the hobby is that everything takes a painful amount of time. I had my first tank up with live rock, live sand, and a small Arsenal of beneficial bacterial 'instant cycles'. I was a little over a month in before the tank cycled and 'stabilized' enough to add fish. Read up on quarantining fish and the potential cost of not doing so. Take it slow, you'll appreciate it more in the end.
That being said, zoas are beautiful and easy. Leathers, Kenya trees, and buttons are a good starter. If you want your tank overrun, green star polyp (gsp) and xenias will do that for you. Just remember that these are animals and are completely depending on you to survive. Have fun!