cPanel is a Unix based web hosting control panel that provides a graphical interface and automation tools designed to simplify the process of hosting a web site. cPanel utilizes a 3 tier structure that provides functionality for administrators, resellers, and end-user website owners to control the various aspects of website and server administration through a standard web browser.
You can utilize WHOIS tool. You can see what nameservers are registered to your domain with WHOIS. You can search for "whois" on a search engine to find a site with a WHOIS lookup tool.
Presently there is no version of cPanel and WHM for OS X Server. But you can still access the cPanel interface through Safari, Firefox or any web browser on a Mac.
To obtain your username and password, you will have to contact your web hosting provider. This is the company to which you pay a monthly fee for your site.
You can change your password with the help of Change Password area.
In the X theme, it is on the main screen.
In the X3 theme, it is under Preferences on the main screen.
Make sure that you do not have any spam filtering software enabled that is intercepting the message. If you have disabled your spam filtering and still do not receive the message, you will require to contact your web host for further assistance.
You can use the Password Protect Directories function to accomplish this. Simply enable password protection and then add the users to whom you wish to give access.
Under the Security menu, go to Password Protect Directories. In this feature, you can modify the password protection settings for your domain. If your main domain asks for a password, modify the settings for public_html.