Tracking Weight Gain
Tracking allows you to know excatly how much for you are consuming instead of guessing. Guessing always results in a wrong number, so you must use tracking to know exactly how many calories you are consuming.
You will want to track your diet and workout plan so you can adjust if necessary. By adjusting one variable at a time you know exactly what works and what doesn't work.
You should track calories, protein, carbs, and fat. Everything else isn't necessary. Also try to start tracking water because wild deviations between the days in water consumed can greatly affect your weight. There are formulas for water usage, but aim to drink enough water to have clear urinations during the day.
One of the best sites for tracking food consumed is Fitday.com. It's the time I use, and it covers everything needed.
Of course, don't forget to track how much you weigh! If you want to gain weight then this is obviously the most important variable to track.