What can be done to increases ones weight...what food or lifestyle can make it possible to have a little more weight ?

Weight: I guess if you trying to gain weight, then your net calorie count should be positive. (meaning you should consume more calories than your burn).

Eat healthy foods: high in calories. Eat 6 meals /day. Work on strength training to build large muscle groups. Work out w heavier weights w fewer repetitions. Sleep at least 8- 9 hrs/night. Hydrate well w water. Foods to help w weight gain: almonds, cashews, pecans, sunflower seeds, flax seeds, walnuts, hummus, avocados, granola, trail mix, dried fruits, protein shakes & bars, lean meats, poultry, fish & smoothies.