I just thinking how to set and send PHP variable with HTML form, from first.php to second.php. Actually my first code looks that:
Just add a new input
with type hidden
within your <form> </form>
<?php $your_php_var=5;?>
</form>
<form action='add.php' method='post'>
<input type="hidden" name="email" value="<?php echo $your_php_var; ?>">
<input type='text' name='account'>
<input type='submit' value='Add'>
</form>
See more here http://www.html-form-guide.com/php-form/php-form-variables.html