Feed the clowns first and then directionally feed the sun corals using either a pipet or a turkey baster.  You need to feed each head individually (they are separate animals instead of one animal with many mouths).  Feed small amounts to each mouth.  If you feed the fish in the tank first, then the coral will slowly open up once it smells the food in the water (it can take 5-15 minutes for all of the heads to open up).  They don't need to be fed every day, but I normally made a routine where you feed certain heads every other day and alternate the heads that are feed every other day.