Go to your campaign screen and find the desired campaign with the non-openers (or non-clickers).
Click the "View report" button
Navigate to the "Overview" tab
Scroll down below the 48h activity graph and click the "lists for non-openers" link. The resulting popup will automatically filter out non-openers for you
Please note that this tooltip appears 24 hours after your campaign is finished
In this final step you can either choose an existing list or create a new list for these non-opener contacts
Go to your Contacts screen, find the specified list and select icon of an arrow facing right on the side of the list name in order to create a campaign using this list:
Send your campaign!