Pass a value from a webpage to a from via the URL

I’m looking for a way to pass a field value, through a URL from a button on a web page to an Infusionsoft form.

For example, the user presses a button on the webpage…

The button opens an Infusionsoft form…

Through the form URL I want to pass a value that I added to the URL to display on the form and populate a contact field.

When the user submits, I want the value I added through the URL to be included in the contact record.

I can create the URL, I just need to know two things:

  1. how to add that field value to display on the form when the form opens
  2. How to make sure the value I passed through the URL is added to the contact record when the form is submitted.

Any thoughts?