In a small mixing bowl, mix together sugar and molasses. Continue to mix until the molasses is completely incorporated into the sugar. This will take 2-3 minutes.
If you need dark brown sugar, add another tablespoon (2 total) to the sugar.
Use and store as you would the store bought brown sugar.
Notes
Tip: to prevent your brown sugar from getting too hard, add a large marshmallow to your container. The marshmallow will dry out, not your brown sugar.