Passing info from a smart capture form into the thank you page

I've created a Data Extension with 14 fields in it. I've used that data extension to create a Smart Capture Form/Cloud Page. Under the submit options there are the Confirmation Message and URL Redirect areas. I'd like to be able to pass some of the form fields dyanmic data to these areas. "Thank you for your submission John" as an example.

I've tried to use an HTML Block on the bottom of the form to set variables, I've tried researching the RequestParam function, and I've attempted to pass info in the URL of the Redirect area to an alternate page.

I fear I'm just not grasping how this is done so any guidance would be appreciated.

Example of what hasn't worked:

%%[VAR @FIRSTSET @FIRST = RequestParameter("FirstName")]%%FIRST: %%=v(@FIRST)=%%