He's trying to access his POP or IMAP account through a web interface. This is only possible if the ISP has that option available. My ISP (strictly as an example only) used to have their own POP/SMTP servers. They also had the option of signing into a specific website to be able to access your email anywhere without having to configure another mail client on another machine. This is why he (the OP) would need to contact his ISP... to see if webmail is an option.
My ISP has since switched to Windows Live servers for their email hosting. That means I can sign in on the Hotmail website and get my mail exactly the same way I would with my Hotmail. However, if his ISP still hosts their own email, then that is not an option.