Webkonsol
- Open your servers web console from the control panel.
- Type op <your name> in the white input field.
Ops.txt
It can also be done from ops.txt which is the config file that specifies the players on your server that has Op status.
- Click Configuration Files in your server's control panel.
- Edit ops.txt.
- Type the name of the player you want to make Op. For each new Op, you will have to create a new line. One line per Op.
- Save the file and restart your server.