Appending a hidden input value to a textarea value?
Here is a little example (Additional information):

function my_form($form, &amp;$form_state) {
  $form['name'] = array(
    '#title' &gt; 'Name',
    '#type' =&gt; 'textfield'
  );

  $form['sec_name'] = array(
    '#title' &gt; 'last name',
    '#type' =&gt; 'textfield'
  );

  $form['submit'] = array(
    '#value' &gt; 'Run',
    '#type' =&gt; 'submit'
  );

  return $form;
}

function my_form_submit($form, &amp;$form_state) {
  $f_name = $form_state['values']['name'];
  $s_name = $form_state['values']['sec_name'];

  drupal_set_message('Hello ' . $f_name . ' ' . $s_name);
}