Wide-Grip Pull-up is a good exercise, and you can always start your back workout with this one. For beginning you can do this exercise normal, afterwards you should add a weighted belt. Also if your shoulders are strong, pulling behind the head is even better.
So, to do this exercise, you will need only a wide grip. Whenever you are ready to start the workout, grab the wide grip with your palms facing forward. As long as your both arms are fully extended, move your torso and head a bit forward too. That will be your starting position, like on picture 1(A).
Whenever you are ready, start pulling up until your elbows and lower hands make a 90 degree angle. If you are pulling behind head, pull up until your back of the neck touches the wide grip. Note that your upper torso must stay stationary and your forearms should only hold the grip. When you hit that position, make a pause for 1-2 seconds, like on picture 1(B), then slowly start to lower your body to its starting position.
You can repeat this exercise for a desired times of reps, just make sure you don’t hurt any muscles, because you are overheating them.