How to Gain weigth in a faster way?

Yes, you can gain weight in a short span of time. I have trouble keeping weight on, and if/when I get sick my weight drops dramatically. (I weigh 95# if I get flu or anything it drops into the 80's and the Dr said it's dangerous for me...I agree!) So, what I do is eat my regular meal, and drink Boost, Ensure, or a milk shake, on top of your normal meal. What you need to do is eat above the level of calories you normally need to maintain the same weight. If you need or usually eat 1800 calories a day, then you need to eat foods with a higher caloric value. Drink ice cream milk shakes made with whole milk (not reduced calorie milk), or whole milk yogurt fruit shakes. To increase the calories and nutritional value, you can add protein powder or brewer's yeast (found at health food stores.) Other foods with good nutrition, but high in calories: avacado, coconut milk, peanut butter (make a sandwich of peanut butter and add honey instead of jelly.) I see you are only in your 20's, so cholesterol shouldn't be a problem for you yet, but still I'd watch how much you intake. It's also a good idea to do some simple excercises so that you are gaining muscle tone along with weight. Without excercise, you will gain weight, but it's more likely to be fat, and not the kind of weight gain you desire.