to show the for information on the thank you page, you will need to first store it in session variables.
There are webassist behaviors for doing this in Security Assist 2 and in eCart.
the steps would be:
On the form page, open the server behaviors panel. click the plus button and select eCart -> General -> Set Session Value (or WebAssist -> Cookies -> Set Session Value if you own Security Assist 2)
For the trigger, click the lightning bolt icon, from the dynamic bindings panel, expand the form collection and select the first for element.
Do the same thing for the Value.
Set the name to be the same as the form element.
Repeat those steps for each form element so that you create a session variable for each one.
On the thank you page open the bindings panel, and expand the session collection, use the session bindings on your page to show the information that was entered in the form.