The first time I read instructions here on BYC I couldn't get it --so I pulled out eggs from fridge and then followed instructions. FinallyI got it.
FLchickens has the eggs in cartons so they are upright moving 45 degrees one way then the other.
My first set, I hand turned x to O and back. Endless hand washing and I did break one despite great care. They get very fragile by the end. I now put them in egg cartons with bottoms torn out (for ventilation) and put a board underneath one end to lift an end and mimic the 45 degrees of a turner. VERY easy. Like a tetter totter. I even mark each end O and X ! I check the eggs a lot anyway (don't trust the temp).
I read a hatching book saying gentle handling the first week especially and the more turning the better: turning 5 times a day has a better hatching rate than 3 which is the minimum recommended. Hens turn eggs about 96 times a day!