Garnish them according to your own taste. The classic way is : salted butter, fried egg, cooked ham, grated cheese. Other choices can be béchamel sauce with mushrooms, minced meat, sausage, Roquefort cheese, etc.
Start by melting a knob of butter in the bottom of the pan. Then place the pancake in the pan to warm it up.
Sprinkle diced ham over the pancake.
Crack the egg on the pancake, sprinkle over the grated cheese. Cook until the cheese is melted and the egg is cooked to your liking.
If you like your egg well done or you are cooking a few galettes to be served at the same time, it would be quicker to cook the eggs separately in a frying pan and then assembly on the galette while still in the crepe pan.
Transfer to a plate. Fold in the edges: traditionally all 4 sides are folded in. I have now started to just fold two sides making a point. When doing this method you would place the egg and most of the ingredients further down the galette (ie not in the centre). Serve hot.