Before being able to add livestock, you have to establish the <<Nitrogen Cycle
>>. This is established by <<"Cycling"
>> a tank for the first time. This may take up to 6 weeks or more, but with the addition of livesand it may be shortened. Can you define what kind of livesand it is? (bagged, made by LFS
, etc) I would also suggest adding liverock as well to enhance the biological filtration and appearance fo
the tank for both you and your livestock.
As far as the clowns, they do not really need to "live" in anything, at least not in aquariums. They form the relationship with anemone's in the wild, but there it is to hide from predators that are absent in home aquariums with the proper husbandry. Whether or not they take to anything you had to locate themselves on or near is up to them....some freely seek out a host while other just hang out by a cave.
If you are looking to specifically setup a tank for clowns, I would highly recommend the book: Clownfishes
by Joyce Wilkerson.