Insert into multi tables by linq to entity

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LINQ

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entity-framework

Hi guys,
I am trying to make a muti step jquery form for uploading resume,
and i send data to db by json and using Linq to Entity,
I have 4 tables:
1- Basic info
2- education info
3- work experience and
4- skills

when user click on submit button i need to add edu and work and skill info into another tables but i need the generated userid to insert into those tables as foreign keys,
dont know how to get id and how to pass it as parameters into those tables:

its my json code:

<script>
        windows.onload = function () {
            $.getFormObject = function (selector) {

                var obj = {};
                var propArr = $(selector).serializeArray();

                $.each(propArr, function (i, p) {
                    obj[p.name] = p.value;
                });

                return obj;

            };

        };
   </script>
<script>
  //  window.onload =
    $(function () {
        $('#btnSubmit').on('click', function () {
            var formObj = $.getFormObject('#msform');
            formObj.Id = 0;

            var dataToSend = { resume: formObj };

            $.ajax({
                url: '/Resume.aspx/AddBaseResume',
                contentType: 'application/json',
                dataType: 'json',
                type: 'post',
                data: JSON.stringify(dataToSend),
                success: function (id) {

                    var $messageContainer = $('.message-container');
                    $messageContainer.html('');
                    $('<div class="alert alert-success" />')
                        .html('Your ID is: ' + id.d)
                        .hide()
                        .fadeIn()
                        .appendTo($messageContainer);

                    //reloadGrid();
                },
                error: function () {

                    var $messageContainer = $('.message-container');
                    $messageContainer.html('');
                    $('<div class="alert alert-danger" />')
                        .html('Oops! Can not add you right now! :(')
                        .hide()
                        .fadeIn()
                        .appendTo($messageContainer);
                }
            });;


        });
    });
  </script>

and its my webmethod:

[WebMethod]
        public static string AddBaseResume(tblResume resume)
        {
            var db = new SHDBEntities1();
            db.tblResumes.Add(resume);
            db.SaveChanges();
            return resume.Id.ToString();
        }

        [WebMethod]
        public static string AddEducation(tblEducation edu)
        {
            var db = new SHDBEntities1();
            db.tblEducations.Add(edu);
            db.SaveChanges();
            return edu.Id.ToString();
        }

thanks in advance for any help or suggestion!