Log in to your list settings (click here for instructions on logging in)
In the upper left portion of the screen, click "Membership Management..."
Click on the image to view full size
Scroll down to the list of members at the bottom
Put a check next to the members you would like to moderate and click the “Submit Changes” button
If you would like to moderate all members, scroll to the very bottom under “Additional Member Tasks” and select the “On” option for the “Set everyone's moderation bit” option, and click the “Set” button