I was a fat kid, however now I'm drastically "under" weight after a major body transformation using diet and exercise. I want to build up lean muscle and get a ripped look. I am now going to the gym 2 or 3 times a week, trying to build up some muscle, but I have a "MAJOR" fear of gaining weight. I know that excess carb intake means you store it as fat, but I don't want to get fat, I want to get lean muscle mass.

The answer you are looking for is balance.  There is an ideal amount of Protein, Carbohydrate and Fat that will allow you to maintain an ideal weight while helping you to accumulate new muscle mass.

Protein is very important as it provides the raw building blocks for new muscle growth while helping reduce muscle breakdown (catabolism).  Secondly, you need carbohydrate to support this muscle growth.  If you don't consume enough carbohydrate, you will find it very hard to put on muscle.  Spreading your carbohydrate intake evenly throughout the day with protein rich foods will help avoid body fat accumulation, as will consuming low GI carbohydrates.

Stop focusing on weight gain and look towards balance in your eating habits while keeping up your healthy exercise.  This will help you maintain your ideal weight.