title: How to change value on PHP?
body: <p>I am new to PHP, I would like to build a PHP page that include a combobox and a submit button. The combobox allow us to select the value of month, Jan,Feb... and so on.
  By default, the value on PHP is: <code>$value="Jan"</code>, if I select the combobox from Jan to Mar, the value on PHP should change to <code>$value="Mar"</code>.
  So, how can I achieve such a functionality?</p>