How to insert the values into Database using LINQ

Source Code:


Imports System.Linq


Partial Class _Default
    Inherits System.Web.UI.Page

    Protected Sub Page_Load(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.Load

        If Not IsPostBack Then
            Dim db As DataClassesDataContext = New DataClassesDataContext()

            Dim data = From emp In db.registers
                      Select emp

            DropDownList1.DataSource = data
            DropDownList1.DataTextField = "email"
            DropDownList1.DataBind()
        End If
     
    End Sub

    Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button1.Click
        Dim db1 As New DataClassesDataContext()

        Dim cust As register = New register()
        cust.fname = TextBox1.Text
        cust.lname = TextBox2.Text
        cust.email = TextBox3.Text
        cust.address = TextBox4.Text
        cust.phnumber = TextBox5.Text
        cust.designation = TextBox6.Text

        db1.registers.InsertOnSubmit(cust)
        db1.SubmitChanges()



    End Sub

    Protected Sub Button4_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button4.Click
        Dim db As DataClassesDataContext = New DataClassesDataContext()

        Dim data = From emp In db.registers
                  Select emp

        GridView1.DataSource = data
        GridView1.DataBind()


    End Sub

    Protected Sub Button2_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button2.Click
        Dim db1 As New DataClassesDataContext()

        Dim cust = (From reg In db1.registers Where reg.email = DropDownList1.Text).[Single]()


        cust.fname = TextBox1.Text
        cust.lname = TextBox2.Text
        cust.address = TextBox4.Text
        cust.phnumber = TextBox5.Text
        cust.designation = TextBox6.Text

        db1.SubmitChanges()

    End Sub

    Protected Sub Button3_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles Button3.Click
        Dim db1 As New DataClassesDataContext()

        Dim cust = From reg In db1.registers
                   Where reg.email.Contains(DropDownList1.Text)
        Select reg

        db1.registers.DeleteOnSubmit(cust)
        db1.SubmitChanges()
    End Sub
End Class

Designing