Here is a step by step guide on how to do this. If you want a picture guide or a video guide please contact me.
Step 1: Start up your server, make sure you are able to click the button "Edit Server"
Step 2: You just need to scroll down below the server icon picker, and right above the MOT editor. type in this command, op <Player Name> .
Step 3: Log into the server and make sure that your username is stated correctly.
Step 4: Say thank you, because thats the nice thing to do