On admgr.liebertpub.com, click the Ad Mgmt button in main navigation.

To change or add information for an existing advertiser, click the hyperlinked letter that corresponds to the first letter of the advertiser's name:

In the list that appears, click the pencil icon next to the advertiser you wish to work on:

Add to or modify the saved data for that advertiser on the form that appears. When you're finished, click the save button: