If pull ups are too hard for you, you can use resistance bands to work your lats and develop your strength.
Anchor the band at the top of the door.
Facing the door, grab a handle with each hand and kneel down on one knee, 3 to 4 feet from the door. Keep your back and head straight. Your arms should be pointed towards the anchor with palms facing down.
Exhale and contract your lats, pulling the handles down until your hands are below your chin.
Inhale and return to the starting position. Repeat.