He needs to go to the their support pages and see if they support POP or IMAP and then find the correct settings for them if supported.
Write or print those instructions down then go to Settings >> Mail, Contacts, Calendars >> Add Account >> Other >> Add Mail Account and enter the data. It might take a little experimentation to get it right, but it should work.
If windstream suport an exchange syncing you could do it that way too, using the Microsoft Exchange option to add an account.