There are obviously many things you can do for the back, but three major exercises I have found improve strength and muscularity for the back, and are also used by friends I know that are truly huge-- regular style deadlifts, chin-ups (all the way down and up; under and overhand), and bent over rows (bar and dumbell). There are again many variations of each exercise, and certainly any exercise thant involves the back muscles will help them get stronger and grow, but to get in the top 1% strong those should be a staple.
I do five sets of five or six for each exercise. In fact, I'm going out with my son in about an hour to do just that. Largest and heaviest weighted exercise to smallest weighted exercise involving less muscles and strain. For example, I'll do deadlifts first, then to chin-ups (weighted), then bent-over rows with dumbells. I do back, biceps, rear delts, hamstrings, calves twice a week. You will have to find what frequency and rep/set schedule works for you. I do vary it depending upon my body's demands. If I've really stressed myself out physically for several weeks, I'll bump it down to three sets of eight for each exercise involving lighter weights for recovery. Other times, if I'm stuck in a strength plateau for awhile I'll bump it to eight sets of three, focusing on big weights.
Watch your diet and get plenty of sleep along with finding the recovery time for your body. Your rep/set amounts will also depend upon what your personal goals are. Mine is functional strength.