You can't tell just from candling if the egg is fertile unless it has been incubated for several days. If you collected it within a day (or even two or three or more) of when it was laid, there is no time for the embryo to develop, even if the momma hen was sitting on it full time.
If you have a rooster with your girls, OR if they had a rooster back at their old home, they will probably be laying fertile eggs. The hens store up sperm from the rooster for up to 3-4 weeks after a successful mating.
Just eat the eggs and don't worry about it - only a very trained eye can tell any difference between fertile and non-fertile eggs as long as they haven't been incubated. There is no difference in appearance or taste. If it IS fertile, it won't develop AT ALL unless it's been incubated either by a broody hen or in an artifical incubator.
Depending on what type of hens you have, they probably wouldn't sit on their eggs anyway, as only a few breeds are consistently 'broody' = meaning they will sit on eggs to hatch them. Most breeds have been bred so they do NOT go broody. For reliable egg production, you want a hen that won't sit on her eggs, but will just continue to lay them on a regular basis.
Hope that helps - if it's clear as mud, feel free to ask away for clarification.
