Web Host manager is located at http://www.yourdomain.com/whm/ or securely at https://your.server.ip:2087 (e.g. https://209.51.153.186:2087 ) It is highly recommended that you log in at the secure url. WHM data is transferred through your browser unencrypted unless you use the secure port. You must have port 2086 and 2087 open on your computer in order to log into WHM. These are open by default, but could be closed if you use a firewall.

More info can be found here:
http://webhost.page-zone.com/