If there's not a hen constantly sitting on them they're not going to hatch, and you won't be able to tell if they're fertile by candling. If a hen had been sitting on them for five days or more you could see an embryo growing by candling, but since it doesn't sound like you have a broody hen I doubt you'll find that. To see if an egg is fertile without a hen sitting on it trying to hatch it you have to crack it open and look for a bull's-eye mark. If you have a rooster or two they're probably fertile. If you're not seeing a chicken on the nest when you're going to check or when you go in to check at night, they're not broody and they're not going to hatch those eggs, sorry.