Did you kit come with any other instructions? The extract kits from my local shop come with fairly detailed instructions. The process is to boil X amount of water (somewhere in the range of 1.5-2.5 gallons), remove from heat and add extract, then top off to 2.5-3.5 gallons. Boil this for 60 minutes, adding hops at the 60 minute, 15 minute, and 2 minute mark. Of course this varies from recipe to recipe so maybe your hop additions are right, but in my experience there have always been 3 hop additions (bittering at 60, flavor at 15, and aroma at 2).