The way I would do it is to create paragraph tags where you want your error messages with the same class and show them when the data is invalid. Here is my fiddle
if ($('#email').val() == '' || !$('#password').val() == '') {
$('.loginError').show();
return false;
}
I also added the paragraph tags below the email and password inputs
<p class="loginError" style="display:none;">please enter your email address or password.</p>