Protein only will help you if you lift.
Get new lifting partners, or lift alone. Simply put, if you want to get bigger, you've gotta lift. As for what is heavy, that depends on YOU. If you're doing a pyramid set like I described above, you go up in weight, and lower the reps, with every set. How much weight you do in each set depends on how much you CAN do.
As for what to do? Everything. For chest, do bench, incline, flies...biceps do different variations of curls, triceps do pushdowns, "skull crushers", dips, for back do lat pulls, pullups, rows, for legs do squats, lunges, leg extensions & curls, calf raises, for lower back do deadlifts, shoulders do shoulder(military) press, lateral raises...
Of course those are just examples, there are tons of different exercises for each muscle group. What I'd recommend is going 3 days a week (MWF is always good), start off doing 1 exercise per muscle group, most or all muscle groups a day, for a couple of weeks to acclimate your body to the exercises. Then start doing muscle-specific days, for examples chest and tris on monday, back and bis on wednesday, legs on fridays...
