Super easy. So easy in fact you will wonder why you didn't make this sooner.
Using a medium cooking pot, add the water, juice and sugar. Heat on medium low until the sugar disolves.
Add the cranberries and turn the heat up a bit to bring to a soft boil.
Let it gently boil, uncovered for about 10 minutes. You may hear some of the cranberries popping. You want them to rupture. Stir regularly
Turn the heat off and using a fork, mash any whole looking cranberries. Let sit for 15 minutes to thicken. Refridgerate