You can choose to have your track be All Rights Reserved, or available through Creative Commons through the track's Metadata tab.
All Rights Reserved - Copyright is automatically granted to you when you begin creating your work. You don't have to file anything anywhere, or publish anything online to own the copyright of your music. By choosing All Rights Reserved, you ask that other creators not use your material.
Creative Commons - With Creative Commons licenses, creators have the choice to give up certain exclusive rights normally associated with copyright, while retaining others. There are six different licenses that provide users with different levels of freedom.