More information is needed, such as the mail provider you're trying to set
up, but I notice that you have apparently got a Yahoo account, so that may
be what you're trying to set up. The short answer here is, you can't,
except....
Standard Yahoo accounts can't be used directly with POP clients like Windows
Mail, OE, Outlook, or Windows Live Mail, Thunderbird, etc.
You would need a 3rd party tool like YPOP or pay Yahoo for their enhanced
service. http://ypopsemail.com/
