If you haven't zested your lemon yet, wash it and then use a vegetable peeler to cut wide strips of zest.
Then put the zest in a cup and add water and a few ice cubes. Let the zest soak in the ice water for 10 minutes to remove extra bitterness.
Next, scoop up your zest and set them on a clean kitchen towel to dry them off. The zest will still be moist even when it's dried, but you don't want any extra water in your sugar.
Then add a couple scoops of sugar into your container followed by a few pieces of lemon zest. You may need to rip the zest in half to get it to lay flat on your sugar.
Then top the lemon zest with a couple more scoops of sugar to cover the zest. Add another layer of lemon zest. You are building layers of lemon zest and sugar.
Keep adding layers of lemon zest and sugar until your container is full, and then top it with a final layer of sugar to completely cover the last of your lemon zest.
Put a lid on your jar or other container, label it, and set it out of direct sunlight. You can use your lemon sugar after just a few days, but the scent and flavor get stronger the longer it sets.