Combine the sugar and molasses in a bowl. Work the ingredients together with a fork until the molasses is completely distributed throughout the sugar.
Store the brown sugar in an airtight container at room temperature.
To make dark brown sugar: You would do the exact same thing as above, but add 2 tablespoons molasses to the granulated sugar.
Substitute maple syrup: Yes traditionally, homemade brown sugar is made with white sugar and molasses, but you can replace the molasses with maple syrup.
How do I keep my brown sugar soft? - First, make sure you are keeping your brown sugar in an airtight sealable container instead of the bag it comes in once it's been opened. Then you can add a piece of white bread or a few marshmallows on top.