Extension talk:AuthorInfo

In AuthorInfo.php I needed to change the 6th line:

$wfAuthorInfoPath = $WPI_URL. "/extensions/AuthorInfo";

without the $ before WPI_URL the path to the javascript was wrong so the extension failed.

Help implantating please
I don't understand where exactly I'm supposed to add  Please advise!!!

Mediawiki 1;20
Doesn' match whit Versio 1.20... Sorry