Dump your blackberries into a bowl. Add the sugar on top. Allow to sit to 15-20 minutes.
Mix the berries and sugar together.
Pour ito a pot. Stir in the pectin.
Bring to a boil. Then reduce to a simmer.
Cook until the jam has thicken. Time will vary, but give yourself at least 10 mins. To test it, place a small amount of the jam onto a plate. Place the plate in the freezer. Check after 1 to 2 minutes. If the jam doesn't move when you turn the plate, it's thick enough. If it runs immediately, then you need to cook it longer.
Place into an air tight container. Put in the fridge or freezer once it has cooled.