WordPress not pointing to “www” address of the site

I am attempting to install wordpress. The non www version of our site (example.com) connects to our intranet and is not allowed to be accessed outside of the school.

We need wordpress to point to the www version of our website.

As of now the wordpress installation is stripping the www off during the installation. And instead of giving you an option to hold on to the www it just gives you a nice little message telling you why the www. is not needed.

Can anyone help