1. Start your Minecraft server.
  2. Log in to the server console.
  3. Type the command op <your username> to give yourself operator status. Replace <your username> with your Minecraft username.
  4. Press Enter to execute the command.

Your Minecraft username now has operator (OP) status on the server.

Note: Giving yourself operator (OP) status grants you access to all server commands, including potentially destructive ones. Be careful with the commands you use.