To achieve a wide physique that fills out your t-shirts you need to build a big back.
The back is made up of a few different groups of muscles that perform different tasks in terms of your body.
The lats are those muscles that are responsible for pulling your body up in the pull-up motion.
The rhomboids are the muscles in the middle of your back that help with pulling things closer to you for example in a rowing motion.
There are a few very good exercises that can help build muscle mass on your back.
These are pull-ups, barbell rows, t-bar rows and deadlifts.
Pull-ups will target your lats and create width.
Perform pull-ups with controlled motion in a repetition range of 8-10.
You may need reach this many to begin with but after a while you will become stronger in this movement.
If 10 repetitions become too easy then you will need to add weight to your body with the aid of a weight belt.
Barbell rows are a very good exercise for building depth in your back making it more solid.
Rows will target the middle of your back as opposed to the lats.
With a row movement with a barbell you must make sure you bend forward from the waist and keep your back straight throughout the movement to keep the focus on the middle of your back.
Be sure to really feel the squeeze of your muscles in the movement and keep your body in a fixed position.
If you move out of position you will not focus the weight on your back and could use other muscles to move the weight which is against the object of the exercise.
Deadlifts are a very good back exercise building the whole back.
Go heavy for 5-7 repetitions to get the most impact.
Make sure to keep your back straight in the move and do not over-extend at the top of the move.