Help❓ minecraft server help

whenever you go onto your server you can use console right?
well whenever you goto server.properties youu see rcon=enabled or something it lets you control your server from phone
i was wonder how to do that
all of the things ive tryed do not work just errors

Alright, frienderino, let's get some stuff out of the way.
Are you portforwarded? Can players join your server from your external IP?
What App are you using? Is it paid or free?
Can you please specify your problems?