How Do I Setup the Image Onload Technique (IOL)?

I really appreciate this guide and the process is notably logical. However, it's still not executing the alert() call. I am currently getting used to the database. Semantically, I may not be interpreting the statement correctly: "Now visit a form that has been configured to include the image onload field..."

Are you referring to the [-] field that you create when you say, "visit a form"? 

Either I didn't follow your guide correctly, which I have read several times now. Or I am misinterpreting what you mean by that statement.

Thanks for the help