Eating more is more important to weight gain than doing the right exercises. First get in the extra calories (aka, protein), then get in the workouts to make sure the calories (aka, protein) builds muscle instead of fat.

The best compound exercises for gaining mass are bench press, squats, deadlifts, pull-ups/chin-ups, dips, and rows. Cardio only increases your metabolism, so doing that will either slow your weight gain, keep you the same, or make you lose weight.

Hope that helps.