customizing validation

customizing validation

Hi guys
I don't want to use a form button submit event, as I am using ( MVC reusable partial pages) so I want the jquery validation with control. In some instances these partial pages appear as modal popups

How do I focus on the required fields and enable the custom error messages.

Here is my code

 $('#Button_Lists_Submit').click(ehi);  // calls the validation code below
      var Submit_Form = function () {
         
                debugger
                var data = $('#List_Form').serialize();
                if ($('#List_Form').valid) {
                  ehi();   // call an ajax post here (which I already have in my code)
                }
                else {
                  
                    return false;
                       form.focusInvalid()   // focus on the form errors as this DOES NOT WORK
                }
               
               
             
            }


  function ehi(e) {
                e.preventDefault()
                
                var fd = new FormData($("#List_Form")[0]);

                var form = $('#List_Form');
                form.validate();
                if (!$('#List_Form').valid()) {
                    alert('Model is not valid -' + form.valid());
                   
                    return false;
                }