รบกวนผู้รู้ช่วยอธิบายโค้ดVB.Net ทุกบรรทัดให้หน่อยนะคะ ... ขอบคุณมากค่ะ

Option Explicit On
Option Strict On

Public Class Form1
    Dim Emp As New Employee

    Private Sub btnCal_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCal.Click
        With Emp
            Try
                .Id = CInt(txtId.Text)
                .Name = txtName.Text
                .Salary = CDbl(txtSalary.Text)

                txtDisplay.Text = .Id.ToString & "  " & .Name.ToString &
                                    vbCrLf & vbCrLf & "หักภาษีเป็นจำนวนเงิน " & .TaxPaid.ToString("#,##0.00") &
                                    " บาท" & vbCrLf & vbCrLf & "เงินเดือนสุทธิ " & .SalaryAfterTax.ToString("#,##0.00") & " บาท"
            Catch ex As Exception
                MessageBox.Show(ex.Message)
            End Try
        End With
    End Sub

    Private Sub btnCancel_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnCancel.Click
        txtDisplay.Text = ""
        txtId.Text = ""
        txtName.Text = ""
        txtSalary.Text = ""
    End Sub

    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load

    End Sub
End Class

Option Explicit On
Option Strict On
Public Class Form1
    Dim max As New FindMax


    Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClear.Click
        txtNum1.Text = ""
        txtNum2.Text = ""
        txtNum3.Text = ""
        txtMax.Text = ""
    End Sub

    Private Sub btnFindMax_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnFindMax.Click
        Try

            If txtNum1.Text = "" And txtNum2.Text = "" Then
                If CInt(txtNum1.Text = ".") = 0 And CInt(txtNum2.Text = ".") = 0 Then
                    txtMax.Text = max.FindMax(CInt(txtNum3.Text)).ToString
                Else
                    txtMax.Text = max.FindMax(CDbl(txtNum3.Text)).ToString
                End If

            ElseIf txtNum2.Text = "" And txtNum3.Text = "" Then
                txtMax.Text = max.FindMax(CDbl(txtNum1.Text)).ToString
            ElseIf txtNum1.Text = "" And txtNum3.Text = "" Then
                txtMax.Text = max.FindMax(CDbl(txtNum2.Text)).ToString
            ElseIf txtNum1.Text = "" Then
                txtMax.Text = max.FindMax(CDbl(txtNum2.Text), CDbl(txtNum3.Text)).ToString
            ElseIf txtNum2.Text = "" Then
                txtMax.Text = max.FindMax(CDbl(txtNum1.Text), CDbl(txtNum3.Text)).ToString
            ElseIf txtNum3.Text = "" Then
                txtMax.Text = max.FindMax(CDbl(txtNum1.Text), CDbl(txtNum2.Text)).ToString
            Else
                txtMax.Text = max.FindMax(CDbl(txtNum1.Text), CDbl(txtNum2.Text), CDbl(txtNum3.Text)).ToString
            End If

        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try
    End Sub

    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load

    End Sub
End Class

Public Class Form1
    Dim myVat As New VAT

    Private Sub btnClear_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnClear.Click
        txtAmount.Text = ""
        txtPrice.Text = ""
        txtTotal.Text = ""
        txtVat.Text = ""
    End Sub

    Private Sub btnOK_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles btnOK.Click
        Try
        If txtVat.Text = "" Then
                txtTotal.Text = myVat.Add(CDbl(txtPrice.Text), CInt(txtAmount.Text)).ToString("#,##0.00")
        Else
                txtTotal.Text = myVat.Add(CDbl(txtVat.Text), CDbl(txtPrice.Text), CInt(txtAmount.Text)).ToString("#,##0.00")
        End If

        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try
    End Sub

    Private Sub Form1_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load

    End Sub
End Class