To begin, go to http://admgr.liebertpub.com. Make sure you're in the correct web property. Make sure you're in the correct web property. If you're not, change the web property.

Next, click the Ad Mgmt button in the top navigation:

Next, navigate to the advertiser you want to work on by clicking the letter that corresponds to the first letter of the advertiser's name:

Once you've found the advertiser, click the file folder icon to view campaigns:

Next, click View Zones for the campaign you want to add the add to:

You can now view zones and add ads. Choose the tab that corresponds to the zone you wish to add the ad to:

Go to the position you wish to add the creative to and click the Delete Ad package link: