To Modify An Existing Account
Click the radio button "View or change existing e-mail accounts". Then click the "Next" button.

To Add A New Account
Click the radio button "Add a new e-mail account". Then click the "Next" button.

A window will open asking what type of server your new e-mail account will work with, click the "POP3" radio button.

Then click the "Next" button.

Proceed to the Third Step