Ajax in edit post? How to? Need help!

Hi. I’m trying to create a metabox with a textbox and a button that allows you to click it to add a new textbox. I know how to create the metabox, etc, but I’m struggling to figure out how to create a button that will add a new textbox using Ajax. At the moment here is the code I’m using but it isn’t working. I would appreciate anyone who could please help me figure this out! I’m even willing to donate some cash 🙂

[Code moderated as per the Forum Rules. Please use the pastebin]