I'm new to this too... but have found when candling darker eggs I couldn't see life for certain until day 7.
Then like everyone says get a good strong SMALL head LED flashlight (so you can cup your hand around it) and do it in complete darkness. Also, once you identify where the air cell is, you can mark it with a pencil.. and the first signs of a chick will be on the side of the egg that the air cell is tipped/ angled the highest.
I've circled the air cell in pencil on all the eggs and when I candle later it helps me find the side quickly where the activity shows best. Also, it helps to be patient and let your eyes adjust to the darkness.. it may look ALL dark at first, but then you'll start to see the air cell and the lighter small end... and the middle area where you can see dark and lighter areas and the movement or pulsing inside the egg.