If you want to bring it up to about 11-12% ABV, it will take about 4-5 pounds of sugar. Bring SG to about 1.085. You might also want to add just a bit of yeast nutrients to make sure the yeast has enough food for the extra sugar. Some folks just dump the sugar in and stir well to dissolve, but the preferred method is to make it up as a syrup by adding the sugar to some water and heating up until well dissolved. Let it cool and add it to the must before adding the water to bring up to 6 gallons(assuming this is a 6 gallon kit).