Validation with VB I cant seem to find the right codes to validate phone, group, GPA

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VB

I cant seem to find the right codes to validate phone, group, GPA.

For a student data entry. Can someone help me please.
FOR A STUDENT DATA ENTRY CAN SOMEONE HELP ME PLEASE

Private Sub btnPhone_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnPhone.Click
      Dim number As Integer
      If txtData.Text.Length = 3 Then
          txtData.Text = txtData.Text + "-"
      End If

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UPDATE from a repost by OP:

Create a VB project called “Students”
Design and create GUI (name all the controls properly)
Create a text file on Notepad called “Students.txt”; add at least 20 entries (records) in the file
FOR VALIDATION I HAVE THIS :

Private Sub btnEmail_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnEmail.Click
        Dim Symbol1 As Integer
        Dim Symbol2 As Integer
        Dim TestString As String

        TestString = txtData.Text
        Symbol1 = InStr(TestString, "@")
        Symbol2 = InStr(TestString, ".")


        If (Symbol1 < Symbol2) Then
            MsgBox("Valid E-mail Accepted")
        Else
            MsgBox("Please re-enter a valid e-mail address")
        End If
    End Sub

    Private Sub btnPhone_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnPhone.Click

        Dim number As Integer

        If txtData.Text.Length = 3 Then

            txtData.Text = txtData.Text + "-"

        End If

(I STILL NEED PHONE, gpa, and group)