How do you gain muscle?

Gaining muscle takes exactly the same amount of focus and preparation as slimming down. Some important information about gaining muscle:

•You can't necessarily build muscle without gaining some fat too.
•There are no magic foods, powders or pills that will permit you to gain muscle and lose weight at the same time. Some people can perform this naturally (again, the genes), but many will gain some fat together with
the muscle.
•Your body is quite different from a bodybuilder--trying to gain mass to appear like them isn't the best idea. They've different muscle
fibers than you and also some may even be obtaining a little help from illegal substances.
•If you are a teenager, you'll have a difficult time changing your body dramatically. It's changing constantly and it'll change even more as time pass.
•Gaining weight requires consuming more and lifting more Gaining muscle mandates that you eat more calories than you burn. For individuals with high metabolisms, that might seem impossible, but if you attempt a few of these tricks, you will find that adding calories for your day is easier than you believe:
•Choose calorie-rich foods like granola, bagels, biscuits, avocados, olives, corn, meat, nuts, peanut butter, milk, yogurt and cheese.
•Add extra calories for your meals by using milk rather than water for soups, sauces and hot cereals.
•Sprinkle powdered milk into casseroles.
•Add calorie-rich foods (like avocado, cheese and dressing) to sandwiches and salads
•Mix beans, meat or cheese into pasta or sides
•Snack on yogurt, shakes, crackers and dip
•Keep a food diary for any week or so to get an concept of what you're eating where you can add more calories
The secret is to add calories without adding an excessive amount of saturated fat. You can also consider downing smoothies or meal replacement shakes in between meals.

Lift, Lift, Lift

When you are your calories in check, you need to start lifting weights. This should help you gain more muscle which help minimize the quantity of fat you gain (even though you should expect to gain some fat too). Folks trying to build muscle should:
•Lift heavy. What this means is lifting enough weight that you could only complete about 6-8 repetitions of every exercise. The last few reps ought to be difficult--the last one should be very hard, but not
impossible.
•Have longer recovery periods between sets
•Have more recovery days between workouts
•Use spotters to prevent injury
•Continue with cardio, but ensure that it stays at maintenance level--around 2-3 times of cardio a week to maintain your heart in shape
•Start having a full body program 2-3 nonconsecutive days per week, if you're a beginner. Let your body a few weeks to obtain used to lifting weights before you decide to tackle more intense routines.

Check out Scooby's Workshop. All free information and no supplement scams. Building muscle is a very long, slow process. Hardcore body builders who don't use steroids should only expect 5-10lbs of muscle growth per year, so it really takes a good 5 year or so of lifting and eating right before you'll get the body you want. Just keep at it, don't take too many breaks and turn your "diet" into a permanent eating habit.

There's this guy on youtube called "Physiquesofgreatness" which I follow. I suggest you go to his channel. He'll have the answers and can explain them better than I can.

Take up martial arts, like Shaolin Kung Fu. The whole body gets trained and the body can get quite ripped. However, the ripness is different from the ripness of a body builder.

I think it would be more normal if you could rephrase your question to something like: Is it normal that I would like to gain muscle mass?

I'm small and thin too but I found a good amount of success from just following the canadian food guide and working out 4 times a week. I was only that consistent for a few months, maybe more, but it still yielded great results. That being said our body types are likely a bit different and so may be your metabolism. You are on the right track in terms of diet.

I assume you also eat protein within the metabolic window after working out?

Cannibalize body builders.