The only ways to get information to your script from a client are cookies, forms, and the URL. You can use cookies to create sessions, where you store the information on the Web server and just pass enough information to find the session data. You can use forms with
hidden elements to pass information to your script that is not entered by the user. Forms which use the
GET method will have the parameters show up in the URL; with the
POST method the parameters will not be visible in the URL.
From your example, it looks like the user may be entering private information you don't want to show up in the URL. In that case, a good solution is to have the user enter the information into a form which uses the POST method, and make sure the server is using SSL so the data is encrypted, and so the browser is more careful with the information in its history.
Hopefully that will be enough to get you started.