I was wondering if anyone could help me. I am trying to add a line of code to my page that can fill in fields of a form using information entered by a user. What I want is to make a list of names and addresses and if a user enters their name, the address fields will be filled in automatically based on the information I have already saved for their name. Thank you for any assistance!!

That's not a very good idea, I think. It invites all sorts of phishing expeditions... Unless you put the whole database in the page (!) it will require a trip to the server anyway, so just do it on the server.

If your database has a record of the person's address or whatever, you know what it is, they know what it is: you can just echo all the details on the confirmation page.

What I need to do with this page actually doesn't have to do with addresses. My bad. I need the form for a RSVP page and when a person enters their name, the other people invited will show up below. I was planning on entering the names into the code itself if possible.

Then it's a straightforward bit of javascript programming. You need either to learn how to do it, or pay someone to do it for you, or of course find someone with time on their hands who will do it for nothing.