I've got a bench with a barbell, dumbbells, pull up bar, and a treadmill, what are some workouts i could do to gain muscle?

Strength training : You'll want to do anaerobic exercises-short all out sprints on the treadmill with recovery periods in between; lower body exercises such as squats, lunges, box jumps, 4 plane straight leg raises; upright single leg balance work, varied ab work for your core; upper body such as pull-ups, push-ups, and other strength training w free weights and the bar-a good trainer should be able to get you going.