Trademark or copyright?

I have a club that only exists on myspace and some guy is trying to request that he takes ownership of the site, so i want to make it official so no one can ever try to take the name or recreate something else with our name. Legally what can I do without having to pay a fee to make it our official group? If i was to change the logo on myspace, what can i put on the logo to make it legally ours? a copyright or a trademark symbol and will this protect us under Australian law?