Instructions
Once you acquire an egg, place the egg among your primary Pokemon. This refers to the six Pokemon that can be found in your start menu and that are carried with you while you play. Since the egg is with your Pokemon, you should have five primary Pokemon and an egg.
Walk around with the egg among your primary Pokemon.
Keep the egg with your primary Pokemon until it hatches. The egg will hatch after you have taken a certain number of steps. The number of steps it takes for the egg to hatch depends on several factors, including egg type and any items you might be carrying.