How do you make a puzzle?


Posting positions/puzzles is not possible using the Android app. I don't know about the iapp.
Why not find a regular computer and a browser? Then it is pretty easy. (although people seem to come here regularly saying they are unable to figure it out.)
https://www.chess.com/forum/view/help-support/a-guide-to-posting-your-games-on-chesscom