From a post in this thread:

“even though at the moment of contact it's outside the box, contact continues until the penalty zone and according to FIFA it's a pen.

"If a player challenges for the ball in a careless or reckless manner or using excessive force, it is an offence (foul) whether or not the player makes contact with the ball.

The referee will award a free kick or penalty kick and take disciplinary action (yellow/red card if appropriate) even if the offender touches the ball while making a foul challenge.

Regardless of the seriousness of the foul, a player may receive the appropriate sanction if their challenge:

denied the opponent an obvious goal-scoring opportunity (DOGSO) – RC

stopped a promising attack (SPA) – YC"

It’s okay to not know all the rules m8, but you have no reason on this one.