Change nextURL on an embedded HTML form?

Change nextURL on an embedded HTML form?

Hi,

I am trying to create an embeddable Zoho form that collects a user's data and creates a lead before serving them the file they request in the form.

I've written a php script that serves the correct file based on a php variable at the end of either nextURL or openURL, but I can't figure out how to change the nextURL parameter with information from the form, and I haven't been able to get openURL to work at all.

I would really appreciate your help getting this to work. Thanks!