There is currently only one configuration setting you will need to make which is the full URL of the MediaWiki api.php file. Navigate to Administer >> Site configuration >> MediaWiki API settings to do this. The URL will usually be of the form:

http://host/path/api.php

It needs to be a full url, so begin with http:// or https:// and end with api.php and note that:

• In some situations (I noticed this on windows Vista and with Drupal installed in XAMPP) you may find apache hangs attempting to access the MediaWiki api if the url begins with http://localhost/, using http://127.0.0.1/ fixed this for me.