If your have chosen to host your own domain you must first point this domain to our server (update nameservers). Nameservers for your domain must be updated from the company where you have purchased / registered your domain name. They usually have section such as 'DNS Management', 'Update Nameservers' or anything similar. You can find the correct nameservers to use by selecting 'View Account Details' after logging in to your control panel. After you have updated nameservers of your domain, it will start working in 24 - 48 hours. You will see message 'Your website is up and running' after visiting your domain.
If you don't have an idea about nameservers and how to update them, please register a new account and choose 'I will choose your free subdomain' option. The subdomain will start working immediately without configuring anything.