Carbs are your friend when you need to put on weight  rice, sweet potatoes, oatmeal, etc. will help you put on weight. You can also eat a lot of it to get your calorie goals. If you’re younger or have a lot of weight to put on, you can get away with eating less healthy things like bread, pasta, even snack food, but I try to avoid those things these days. Also, as previously stated,  every meal should have vegetables when possible so your body can properly manage all those calories as they move through your body and come out.