I am naturally very small/thin. what are some ways to gain healthy weight? but still stay fit? what should i be eating and what workouts should i do?

Eat healthy high: calorie foods. Eat 6 meals/day. Work on strength training to build your large muscle groups. Workout w heavier weights w fewer repetitions. Sleep at least 8 to 9 hrs/night. Hydrate well w water. Foods to help w healthy weight gain: almonds, cashews, pecans, sunflower seeds, flax seeds, walnuts, hummus, Avocados, granola, trail mix, dried fruits, extra virgin olive oil, canola oil, protein shakes,