Site manager's manual 11.4 (also same section in list owner's manual,
I think):

 List owners who have only one or just a few lists running on the server
 will be presented with a drop-down list box from which they can choose
 the list they want to work on (only their own lists will be displayed).
 Site maintainers will either see the drop-down list box (on servers with
 up to 51 lists) or a plain text box (on servers with 52 or more lists).
 Either type or choose the name of the list you want to work on, and click
 the button for the operation you want to perform.

Nathan