Example: you have an HTML form where <form method="POST" action="franceresult.php"> and <input name="FmDeptNo" ...> The user enters, say, "61" into the form and hits "Submit".
This will open a page "franceresult.php". On that page, you will have set a variable within the php code tags (e.g.): "$DeptNo = $_POST["FmDeptNo"];". This should be the first item on the page. In the example, $DeptNo will now hold the value "61". You then use the variable to perform the required action (e.g. query a MySQL database etc.).