First - create a table in your database called personal_notes with the following fields: note_id, profile_id, personal_note, date (make this update on submit), input_by
then put this in a php block:

 
$profileID = getID( $_GET['ID'] );
$gNote = mysql_query("SELECT * FROM personal_notes WHERE `profile_id` = '" . $profileID . "' AND `input_by` = '" . $_COOKIE['memberID'] . "' ORDER BY note_id DESC LIMIT 1");
while($row = mysql_fetch_array($gNote ))
  {
  $pNote = $row['personal_note'];
  }
$aForm = array(
            'form_attrs' => array(
                'name'     => 'form_personal_note',
                'method'   => 'post',
            ),

            'params' => array (
               
                    'db' => array(
                    'table' => 'personal_notes', // table name
                    'key' => 'note_id', // key field name
                    'uri' => '', // uri field name
                    'uri_title' => '', // title field to generate uri from
                    'submit_name' => 'submit_personal_note_form', // some filed name with non empty value to determine if the for was submitted,
                                                       // in most cases it is submit button name
                ),
                'csrf' => array(
                      'disable' => true, //if it wasn't set or has some other value then CSRF checking is enabled for current form, take a look at sys_security_form_token_enable to disable CSRF checking completely.
                )
              ),

            'inputs' => array(
                'header1' => array(
                    'type' => 'block_header',
                ),
                'personal_note' => array(
                    'type' => 'textarea',
                    'name' => 'personal_note',
                    'html' =>  true,
                    'value' =>  $pNote,
                    'colspan' => 2,               
                      'db' => array (
                        'pass' => 'XssHtml',  
                    ),
                ),
                'profile_id' => array(
                    'type' => 'hidden',
                    'name' => 'profile_id',
                    'value' => $profileID,    
                      'db' => array (
                        'pass' => 'Xss',  
                    ),
                ),
                'input_by' => array(
                    'type' => 'hidden',
                    'name' => 'input_by',
                    'value' => $_COOKIE['memberID'],    
                      'db' => array (
                        'pass' => 'Xss',  
                    ),
                ),
                
             'submit_send' => array(
            'type' => 'submit',
            'name' => 'submit_personal_note_form',
            'colspan' => true,
            
            'value' => _t("_update_personal_note"),
        ),
             ),

        );

        $oForm = new BxTemplFormView ($aForm);
        $oForm->initChecker();

        if ($oForm->isSubmittedAndValid ()) {

            // add additional vars to database, in this case creation date field is added
            $aValsAdd = array (
            );
if ($oForm->insert ($aValsAdd)) {
$sStatusText = '_personal_note_updated'; 
            }
        }
                if($sStatusText) {
            $sStatusText = MsgBox(_t($sStatusText), 3);
                }
        return array($sStatusText . $oForm->getCode(), array(), array(), false);
 
 Then create your language keys and clear your cache.
I have not tested, but should give you a starting point.