Adding Numbers to a PDF


I am trying to add numbers to my merged PDF document.  I found this answer from a previous post:

"Of course is this possible. You cann add page number with a function (AddPageNumberToPDFFile) from the pdfforge.dll coming with PDFCreator and a script."

I don't know what to do with this information.  I don't know how or where to add a fuction.  If someone could provide detailed instructions on how to do this, that would be truly helpful.