<form class="form-horizontal" role="form" id="form-crear-usuario">
                <div class="form-group">
                    <label for="first_name" class="col-lg-2 control-label">Nombre</label>
                    <div class="col-lg-9">
                        <input type="text" class="form-control" id="first_name"
                               placeholder="Nombre" data-bind="value:First_name">
                    </div>
                </div>

                <div class="form-group">
                    <label for="last_name" class="col-lg-2 control-label">Apellido</label>
                    <div class="col-lg-9">
                        <input type="text" class="form-control" id="last_name"
                               placeholder="Apellido" data-bind="value:Last_name">
                    </div>
                </div>

                <div class="form-group">
                    <label for="email" class="col-lg-2 control-label">E-mail</label>
                    <div class="col-lg-9">
                        <input type="email" class="form-control" id="email"
                               placeholder="E-mail" data-bind="value:Email">
                    </div>
                </div>

                <div class="form-group">
                    <label for="pass" class="col-lg-2 control-label">Contraseña</label>
                    <div class="col-lg-9">
                        <input type="password" class="form-control" id="pass"
                               placeholder="Contraseña" data-bind="value:Password">
                    </div>
                </div>

                <div class="form-group">
                    <label for="rep-pass" class="col-lg-2 control-label">Repetir Contraseña</label>
                    <div class="col-lg-9">
                        <input type="password" class="form-control" id="pass2"
                               placeholder="Contraseña" >
                    </div>
                </div>

                <div class="form-group">
                    <div class="col-lg-12">
                        <button class="btn btn-default" id="btn-crear-user" data-bind="click: guardar">Crear</button>
                    </div>
                </div>
            </form>

(function () {
    'use stric'

    function UserViewModel() {
        var self = this;
        self.Active = ko.observable(true),
        self.Email = ko.observable(),
        self.First_name = ko.observable(),
        self.Id = 1,
        self.IdVirtual = "a",
        self.Last_name = ko.observable(),
        self.Login = "a",
        self.Password = ko.observable()
        //pass2: ko.observable(""),

        self.guardar = function (e) {
            console.log(ko.toJSON(self));
            //var datos = { Nombre: nombre.value, Apellido: apellido.value, Email : email.value, Pass : pass.value, Pass2 : pass2.value};
            $.ajax({
                type: 'POST',
                url: '/User/Create',
                data: ko.toJSON(this),//datos,
                dataType: "json",
                beforeSend: function () {

                },
                success: function (data) {

                },
                error: function (jqXHR, textStatus, errorThrown) {

                }
            });

        }
    }


    ko.applyBindings(new UserViewModel())
}());

[Table("User")]
    public partial class User : Entity<int>
    {
        public int Id { get; set; }

        [StringLength(50)]
        public string Login { get; set; }

        [StringLength(50)]
        public string Password { get; set; }

        [StringLength(50)]
        public string First_name { get; set; }

        [StringLength(50)]
        public string Last_name { get; set; }

        [StringLength(50)]
        public string Email { get; set; }

        public bool? Active { get; set; }
    }

[HttpPost]
public async Task<JsonResult> Create(User NewUser)
{
    try
    {
        var resp = await this.iUsersService.CreateUser(NewUser)
        return Json(resp, JsonRequestBehavior.AllowGet);
    }
    catch
    {
        return Json(false, JsonRequestBehavior.AllowGet);
    }
}