If you want to allow non-Whitman people to work on files in your netFiles space, you will have to create something called a ticket. Just like a concert or other event, a ticket grants the ticketholder access. The ticket can be made in such a way that it allows the ticketholder to add, remove or modify files on your netFiles space. You will still have access to these files as well, so you can collaborate on a file or set of files. Because you will be giving permission to someone else to modify your account, you'll be setting up the ticket to affect only a directory within your account, rather than your entire account.
You can always come back to Manage > Tickets to edit and email your tickets. The Tickets screen also shows you the ticket link if you decide to send the ticket another way (i.e. instant messaging). Unfortunately you can only grant either Viewer or Contributor access with Tickets.