If you want to gain a few pounds than you can try to add some high calorie foods to your diet. High calorie foods can include milk products like butter, cheese, cream, ice cream, ghee, cakes, pastries, cookies, etc, Include one of these items in your meals. For example if you are having noodles in lunch then add cheese to it and warm it a little till it melts. This will make the same food higher in calories. If you like to have tea, then add cream to it rather then milk. Cow milk has just adequate calories - not high, not low. Some foods that are high in
proteins are also good. High protein foods are soya milk, non-veg, eggs, cottage cheese, tofu, beans, nuts.
Take 3 proper meals and 3 - 4 snacks in a day. Also include fruits or vegetables in upto 5 meals/snacks. This will keep the fiber content high and make the meal more nutritious.
Exercise of upto 20 min a day should also help.
This should help you gain a few kilos.
Let me know if I can assist you further.