Make the simple syrup: Add both the sugar and the water to a medium sized pot. Then place this pot on your stove, over a high heat. Let this mixture come to a low boil, and stir the ingredients until the sugar dilutes into the water (this should only take a couple minutes).
Add the cranberries: Once the simple syrup has been made, quickly toss in the cranberries. Then stir the cranberries into the simple syrup, and let everything come back to a boil. Once it has come to a boil, lower the heat and let it all simmer for about 10 minutes, or until most of the cranberries have burst.
Let sit: After the above step has been completed, take the pot off of the stove, and let it cool down about 10 to 20 minutes. Once it has done that, then you can pour the sauce into a container, and let it chill in your fridge overnight.