document.forms[0].elements[0].focus()

function checkFormContact(f)
{
  var email_chars;
  if(!f.name.value)
  {
    alert('Nombre?');
    f.name.focus();
    return false;
  }
  if(!f.email.value)
  {
    alert('Correo electronico?');
    f.email.focus();
    return false;
  }
  email_chars = /\b[A-Z0-9._%-]+@[A-Z0-9.-]+\.[A-Z]{2,4}\b/i;
  if(!f.email.value.match(email_chars))
  {
    alert('Por favor verificar correo electronico.');
    f.email.select();
    f.email.focus();
    return false;
  }
  if(!f.message.value)
  {
    alert('Mensaje?');
    f.message.focus();
    return false;
  }
  if(!f.security_code.value)
  {
    alert('Texto de la imagen?');
    f.security_code.focus();
    return false;
  }
  return true;
}