You need to have calorie rich n protein rich well balanced meals. Along with proper work out schedule. You can connect to any dietician for personalized diet plan suited best in your lifestyle and body type. Till then you can follow these, have heavy dinner comprised of good protein, if you are non vegetarian then you can have eggs, fish and lean meat. Or dal or chana or sprouts, Whole grain roti etc.
Next Steps
Have pre n post work out snack like oats or eggs, milk shakes etc. Drink enough water.