To apply an attribute to a List first create your List. Go to Audience > Lists > New List. After you created a list, click on the Take Action button next to the list name that you would like to apply an attribute to.
Click on the "Apply Attribute" button in the Actions Modal.
Select the attribute you'd like to apply from the dropdown list. Then, add the value for that attribute that you'd like applied to the entire List. If your attribute doesn't already exist you will first have to create your attribute in Settings.