First find out what your nutritional requirements are, like how many calories/protein/carbs/ you need to get results. You can either ask an expert or google search information on it.
As for training, I would recommend compound exercises: Squats, deadlifts, and bench press. Also a few body weight exercises like push ups and pull ups don't hurt. You don't have to perform isolation exercises like arm curls or leg extensions because your entire body is being utilized by squats and deadlifts alone. Bench press will help build your upper body.
It's best to work out 2-3 times a week for this kind of strength training and eat a lot. Plan your meals and count your calories, protein, etc. It's easiest to try for 5-6 meals spread throughout the day, because if you have a fast metabolism you won't be able to repair muscle tissue fast enough to make gains, and you'll get tired from not refueling your body enough.
Include one rest day in between each workout.
