you shouldn't keep more than 2 clownfish in one tank unless u have a big enough tank for more than one pair.
u dont really have to do anything to get it in there. if the clown is wild then it will most likely take to the anemone as soon as it sees it. tank bred usually tank some time, some never even host anemones. it all depends on luck really. ive had a few of tomato clowns and they always hosted my anemones. in my opinion, tomatoes and maroon clown fish are the best hosting clownfish in the hobby. bubble anemones are your best bet. also i wouldnt add an anemone untill your tank is over 6 months old... sooooo you have to wait a bit, they need mature tanks with lots of bacteria.