There are a couple of ways that you can do this. You can either copy and paste from the original pages into your new SiteAssist pages, or you can create new pages based on the SiteAssist template, then edit your SiteAssist site to include these new pages.
If you copy and paste you will need to ensure that you get all of the server side code in the new pages above the doctype declaration, then you will copy the form and contents of the page into the body of the SiteAssist pages.