2 Page survey form in PHP with only few details required

Hi,
We have a PHP feedback form which is like a survery broken into 3 pages. The first page asks user some questions and they have to answer all & press Next button. They are taken to a 2nd page where they should answer some more questions. This page has 2 buttons. One is previous button, so that they can go back & change their selection and a Next button so that they can move to the 3rd page. On the third page, they will be asked their details like Name, Email & Comments and when they click submit, the form should mail us all the details from all the 3 pages and send the user an acknowledgement that their submission has been received.

(Maybe we can use SESSIONS but I don’t know how to do that)

So all we have to do is to make sure that all the details from the page 1 get carried over to page 2 & the details from page 1 and 2 get carried to page 3 collectively 2. Also we have to see that the users can go back to the previous pages & edit the data if needed.But the page should still remember their previously filled data. It makes no sense if they can’t see properly what they have filled in perviously. They can select a different option and then resume to the other pages & the info that is being carried over should be updated as well. In short the form data should be updated depending on user actions.

I would appreciate it if anyone can provide with a quick answer as I need this for a page Iam going to set this up shortly. Iam attaching the .html files in the zip just so you could attach the PHP file to it.

Thank you & looking forward to solutions.