Everyone who has main character selected will be entered in a random drawing for 5,000 Maple Points! We will be selecting 20 winners on September 9th , so come on and log in , and select your main character!
Come to members log-in page to select your main character, and then select the world that you have a character in then select your main character. Finally press bottom change main character.

More information on the Maple story official website.