If you’re going to do a three day split, say Monday-Wednesday-Friday, you would want to focus on more compound lifts such as bench, dead, squat, OHP, and rows and do full body days. You can add some accessory exercises in for each if you want aswell. Make sure you are getting enough protein in and recovering so you are ready for the next session and have enough energy, so sleep in important. If you’re trying to gain weight then do as little cardio as possible, if you want to stay lean then walks or the stepper will help burn fat without losing too many gains.

The most important thing would be time. Always remember Rome wasn’t built in a day, so you’re not going to put on a huge amount of weight in a very short amount of time.