Assuming you have made the initial payment, then your website is ready.  However, domains take time to propagate the DNS (domain name servers,) usually 24-48 hours.  So accessing your website via domain can be delayed.

When signing up for shared or reseller services, you will have received an e-mail listing your domain name, username, password, and ip address.

Before DNS Propagation:

To Access Website:
http://AccountIP/~ControlPanelUsername/

To Access Shared Control Panel:
http://AccountIP:2082

To Access Reseller Control Panel:
http://AccountIP:2086

After DNS Propagation:

To Access Website:
http://mydomain.com

To Access Shared Control Panel:
http://mydomain.com/cpanel

To Access Reseller Control Panel:
http://mydomain.com/whm