Girl ignore the motherless attention seeker in the comment and let me give u an advice... Depends on the way u want to put on weight ... but it all comes down to building your appetite. If u want to gain weight in the fast and unhealthy way, i suggest you eat foods with high carbs like potatoes, bread, pasta, sugary foods, etc. Sweets like chocolate and cake beye gizew meblat will spike ur glucose level and make your appetite high. This being said, limit your movements to avoid burning energy. If you want to gain weight slow and healthy, i suggest high protien foods like eggs, milk (any diary product), tuna, meat and protien shakes made with sweet fruits (like banana) with peanut butter and honey. Eating oats every morning helps a lot too in building more appetite. The exercises you need to do should be targeted towards building your body rather than burning fat too.