To tell if an egg is fertilized you have to crack it open and look for a white bulls-eye on the yolk, but if a rooster has access to the hens then you can bet they are fertilized. If you want the hens to hatch eggs then don't collect the eggs, just leave them in the nest and once the pile is big enough a hen will usually go broody and sit on them 23.5 hours of the day for 21 days and hatch them. Just make sure that the breed of chicken is prone to broodyness because some production breeds have had the urge to hatch chicks bred out of them in favor of maximum egg production. Bantam breeds and Game breeds to name a few are very prone to going broody, Leghorns and Black Stars are not. You candle the eggs only after they have been incubating for a few days, candling fresh eggs will not do any good. An incubator is a good idea because hens won't always hatch chicks on your schedule. I recommend a DIY incubator- Styrofoam cooler with digital thermostat, computer fan and a lamp they cost about $70~$90 to make and work better than many store-bought incubators.
