Commands

Hi. I am relatively new to Minecraft and the Aternos servers themselves. I tried using commands in game after looking up the lists of them, and it says that I need to contract the Administrator of the server for permission. I started the server off of the Aternos site... Is their some option I am suppose to activate first before using them? I’m curious to use commands based off of what I have seen in videos. I love games like this.

Ok.. I tried doing that but it still says that I don’t have permission to do that action to contact my servers administrator.