As the creator of a room, you have the ability to set room staff. There are two different ways you can do this.

    Type /setRoleName @username in the chat, where RoleName is the role you want to set, and send the message.

    Click on the user-list. Find the user you want to promote. Click on their name and click on the role you want to promote them to.

Check out which role has what perms by clicking the Role Perms tab while in the Mod area.