You'd be better off setting up a free Gmail account instead. Gmail is not only superior in every way, but they also allow for automatic forwarding: »support.google.com/mail/ ··· er=10957
If you have a gmail account you could have it automatically integrate your windstream mail into your gmail inbox or have it append its own separate label so keeps them separate. Then when you send an email you choose whichever email address you wish to send it with. As for creating additional email addresses, go to Windstream.net and click on my account. Log in using your primary email address and you should be good from there.
EDIT: If you do go the gmail way, go to accounts and import. There you can choose add a pop3 account. That way you can check your email where ever you go and what ever device you use. As for me, I keep my gmail and windstream email separate. But I also make heavy usage of custom labels to keep my inbox a lot neater.