If ammonia is reading anything other than ZERO your cycle is not complete, and there should not be any fish in the tank. You proably want to return the damsels to the lfs
anyway as they have a nasty reputation for bullying other fish (very territorial). If you can return the clowns and add a lot more rock (1˝-2 pounds per gallon capacity) that would be ideal. Let the tank complete the cycle then add livestock.
Read the articles on this forum and keep asking questions. For new tanks there are the inevitable questions that will be asked whenever you ask for help. It will save time if you can answer as many as possible in your original post. Posting asking for advice on equipment you are about to buy is also a good way to save money in the long term. The folks here can steer you away from bad advice received elsewhere. Also post your stocking intentions before buying a new fish to make sure you don't have compatiblity or size problems down the road.
Here's my standard list of questions:
please post the following info:
Do you add any chemicals to the tank? (ie. Buffers or Supplements)
What do you feed the tank? (Frozen, Flake or Pellet)
What kind of Salt Mix do you use? Do you let it sit for 24hrs with a powerhead and heater to airate and mix fully?
Do you use RO
water? How do you Top Off evaporated water?
Oh and ......