short position on moble international app.

Can someone clarify to me in easy straightforward step-by-step tips on how to open a short place on binance (not US) cellular app, the right way to put a short place. Am i purported to borrow secure coin or borrow the asset i need to brief? Ive tried multiple time watch binance academy tutorials. And nothing works. Can any of display report how one can do it. This margin buying and selling not futures.