I have checked this form in Myreviews 2.1rc
This is the modfile.php file complete
 // $Id: modfile.php,v 1.1 2004/01/29 14:45:12 buennagel Exp $ 
//  ------------------------------------------------------------------------ // 
//                XOOPS - PHP Content Management System                      // 
//                    Copyright (c) 2000 XOOPS.org                           // 
//                                                    // 
// ------------------------------------------------------------------------- // 
//  This program is free software; you can redistribute it and/or modify     // 
//  it under the terms of the GNU General Public License as published by     // 
//  the Free Software Foundation; either version 2 of the License, or        // 
//  (at your option) any later version.                                      // 
//                                                                           // 
//  You may not change or alter any portion of this comment or credits       // 
//  of supporting developers from this source code or any supporting         // 
//  source code which is considered copyrighted (c) material of the          // 
//  original comment or credit authors.                                      // 
//                                                                           // 
//  This program is distributed in the hope that it will be useful,          // 
//  but WITHOUT ANY WARRANTY; without even the implied warranty of           // 
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the            // 
//  GNU General Public License for more details.                             // 
//                                                                           // 
//  You should have received a copy of the GNU General Public License        // 
//  along with this program; if not, write to the Free Software              // 
//  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA // 
//  ------------------------------------------------------------------------ // 
 
include "header.php"; 
include_once XOOPS_ROOT_PATH."/class/xoopstree.php"; 
include_once XOOPS_ROOT_PATH."/class/module.errorhandler.php"; 
include_once XOOPS_ROOT_PATH."/include/xoopscodes.php"; 
 
$myts =& MyTextSanitizer::getInstance(); // MyTextSanitizer object 
$mytree = new XoopsTree($xoopsDB->prefix("myReviews_cat"),"cid","pid"); 
 
if(isset($HTTP_POST_VARS['submit'])) 
  { 
    $eh = new ErrorHandler; //ErrorHandler object 
    if(empty($xoopsUser)){ 
        redirect_header(XOOPS_URL."/user.php",2,_MD_MUSTREGFIRST); 
        exit(); 
    } else { 
        $ratinguser = $xoopsUser->getVar('uid'); 
    } 
    $submit_vars = array('lid', 'title', 'url', 'homepage', 'descriptio', 'logourl', 'cid'); 
    foreach($submit_vars as $submit_key) { 
        $$submit_key = $HTTP_POST_VARS[$submit_key]; 
    } 
    $lid = intval($lid); 
 
    // Check if Title exist 
    if (trim($title)=="") { 
        $eh->show("1001"); 
    } 
    // Check if HOMEPAGE exist 
    if (trim($homepage)=="") { 
        $eh->show("1016"); 
    } 
    // Check if Description exist 
    if (trim($descriptio)=="") { 
        $eh->show("1008"); 
    } 
 
    $url = $myts->makeTboxData4Save($url); 
    $logourl = $myts->makeTboxData4Save($logourl); 
    $cid = intval($cid); 
    $title = $myts->makeTboxData4Save($title); 
    $homepage = $myts->makeTboxData4Save($homepage); 
    $description = $myts->makeTareaData4Save($descriptio); 
    $newid = $xoopsDB->genId($xoopsDB->prefix("myReviews_mod")."_requestid_seq"); 
 
    $sql = sprintf("INSERT INTO %s (requestid, lid, cid, title, url, homepage, logourl, description, modifysubmitter) VALUES (%u, %u, %u, '%s', '%s', '%s', '%s', '%s', %u)", $xoopsDB->prefix("myReviews_mod"), $newid, $lid, $cid, $title, $url, $homepage, $logourl, $description, $ratinguser); 
    $xoopsDB->query($sql) or $eh->show("0013"); 
    $tags = array(); 
    $tags['MODIFYREPORTS_URL'] = XOOPS_URL . '/modules/' . $xoopsModule->getVar('dirname') . '/admin/index.php?op=listModReq'; 
    $notification_handler =& xoops_gethandler('notification'); 
    $notification_handler->triggerEvent('global', 0, 'file_modify', $tags); 
    redirect_header("index.php",2,_MD_THANKSFORINFO); 
    exit(); 
 
  }//End if 
 
 
    $lid = intval($HTTP_GET_VARS['lid']); 
    if(empty($xoopsUser)){ 
        redirect_header(XOOPS_URL."/user.php",2,_MD_MUSTREGFIRST); 
        exit(); 
    } 
    include XOOPS_ROOT_PATH."/header.php"; 
    $result = $xoopsDB->query("SELECT cid, title, url, homepage, logourl FROM ".$xoopsDB->prefix("myReviews_downloads")." WHERE lid=".$lid." AND status>0"); 
    list($cid, $title, $url, $homepage, $logourl) = $xoopsDB->fetchRow($result); 
    $title = $myts->makeTboxData4Edit($title); 
    $url = $myts->makeTboxData4Edit($url); 
    $homepage = $myts->makeTboxData4Edit($homepage); 
    $logourl = $myts->makeTboxData4Edit($logourl); 
    $result2 = $xoopsDB->query("SELECT description FROM ".$xoopsDB->prefix("myReviews_text")." WHERE lid=$lid"); 
    list($description)=$xoopsDB->fetchRow($result2); 
    $description = $myts->makeTareaData4Show($description); 
     
        include XOOPS_ROOT_PATH . "/class/xoopsformloader.php"; 
        include XOOPS_ROOT_PATH . "/class/wysiwyg/formwysiwygtextarea.php"; 
     
        $sform = new XoopsThemeForm( _MD_REQUESTMOD, "storyform", "modfile.php" ); 
        $sform->addElement( new XoopsFormText( _MD_FILETITLE, 'title', 50, 80,$title ), true ); 
        $sform->addElement( new XoopsFormText( _MD_DLURL, 'url', 50, 80,$url ), false ); 
        $sform->addElement( new XoopsFormText( _MD_HOMEPAGEC, 'homepage', 50, 80,$homepage ), false ); 
        $sform->addElement( new XoopsFormText( _MD_SHOTIMAGE, 'logourl', 50, 80,$logourl ), false ); 
        $sform->addElement(new XoopsFormHidden('lid',$lid)); 
        $wysiwyg_text_area= new XoopsFormWysiwygTextArea(  _MD_DESCRIPTIONC, 'descriptio', $description , '100%', '400px',''); 
        $wysiwyg_text_area->setSkin("xp"); 
        $sform->addElement( $wysiwyg_text_area ); 
         
        $button_tray = new XoopsFormElementTray( '', '' ); 
        $button_tray->addElement( new XoopsFormButton( '', 'submit', _MD_SENDREQUEST, 'submit' ) ); 
        $sform->addElement( $button_tray ); 
        $sform->display(); 
     
    include XOOPS_ROOT_PATH.'/footer.php'; 
?>  
Take it as example to do the job with other forms on this module.