Post the complete rule you want me to explain to you.
Sure. Here are the complete Items 1 and 2 from 2014.
Item 1: Player Going to the Ground.
If a player
goes to the ground in the act of catching a pass (with or without contact by an opponent), he must maintain control of the ball throughout
the process of contacting the ground, whether in the field of play or the end zone. If he loses control of the ball, and the ball touches the ground before
he regains control, the pass is incomplete. If he regains control prior to the ball touching the ground, the pass is complete.
Item 2: Sideline Catches
If a player
goes to the ground out-of-bounds (with or without contact by an opponent) in the process of making a catch at the sideline, he must maintain
complete and continuous control of the ball throughout the process of contacting the ground, or the pass is incomplete.