We begin to login at the 'Members' section located in the top menu. This is the Login Page for the Client Area which contains a line for the email address and a password. They are different than the login details for your cPanel.
Enter your email address. Then enter your Password. Now click on Login. That's all. You are now logged into your account and can begin to manage your hosting services, invoices, billing information, and more.
When you are done, click on the Logout Link in the upper right corner. You are now logged out of the account. There is a Click here to Continue link. Click that link. This will take you to the "Members" section.