[help me please hostgator user] How to redirect Addon Domain [Host gator]

hello yesterday i buy new domain. but when add that domain to host gator than
i can access this domain in following 3 different ways:

www.addonDomain.com
www.primaryDomain.com/addonDomain.com
www.addonDomain.primaryDomain.com

so how can i access this domain 1 one way.
www.addonDomain.com

please help me if you can .