you have to get a trap which i think can range in price from not so expensive to expensive but a cheap one will usually do. and then trap them if your area permits that for TNR and then if they are feral, though now they are called community cats, but there is usually a steep discount to get them done, first shots, rabies is usually included I think and discounts on flea treatments i had one female that took a year and a half to catch and she kept having litters and i kept doing them and then finally got her.