if you know what you are doing and are willing to work hard, look up the PHAT workout, and learn how to bulk. if inexperienced, some good starting programs include stronglifts 5x5, starting strength,simple power based routine etc. either way, squats, deadlifts, pullups/bent over rows, standing press and bench press should be the foundation of you workout plan. one thing people dont usually realize when they try to eat more to gain weight is you cant just eat a bigger dinner, you need to eat more all day long and if your skinny as fuck, a little fat wont hurt. protein powder and a gym membership should be the only thing you need to buy for now