Understanding Datagridview Printing

hello guys i just need help in understanding this block of code. this code is a datagridview printing code that i want to edit to suit my needs but i dont know where to start i tried searching youtube tutorial but i cant seem to find any that explain this(printdocument control). so i want to make the margin a little narrow and to change font for column header and records. i tried changing default/properities of the datagridview and exploring a bit changing all numbers i see in the block of code but i cant seem to understand how it works. and if possible i also want to add a header where i can put a logo.

Private Sub pd_PrintPage(ByVal sender As Object, ByVal e As System.Drawing.Printing.PrintPageEventArgs) Handles pd.PrintPage
        Try

            Dim actualWidth As Integer = dgvInventoryLog.Columns.Cast(Of DataGridViewColumn).Sum(Function(c) c.Width)
            Dim percentage As Decimal = CDec(((100 / actualWidth) * e.MarginBounds.Width) / 100)
            Dim header As String = "Inventory Log"
            Dim footer As String
            Dim startX As Integer = e.MarginBounds.Left
            Dim startY As Integer = e.MarginBounds.Top
            Dim r As Rectangle

            Dim headerFont As New Font(dgvInventoryLog.Font.FontFamily, 15, FontStyle.Italic, GraphicsUnit.Pixel)
            Dim szf As SizeF = e.Graphics.MeasureString(header, headerFont)
            e.Graphics.DrawString(header, headerFont, Brushes.Black, e.MarginBounds.Left + (e.MarginBounds.Width - szf.Width) / 2, startY - szf.Height)
            footer = "Page " & pageCounter.ToString
            szf = e.Graphics.MeasureString(footer, headerFont)
            e.Graphics.DrawString(footer, headerFont, Brushes.Black, e.MarginBounds.Left + (e.MarginBounds.Width - szf.Width) / 2, e.MarginBounds.Bottom + 5)

            startY += 5

            'this is the text alignment
            Dim sf As New StringFormat
            sf.Alignment = StringAlignment.Center
            sf.LineAlignment = StringAlignment.Center

            Dim gridFont As New Font(dgvInventoryLog.Font.FontFamily, dgvInventoryLog.Font.Size, FontStyle.Regular, GraphicsUnit.Pixel)

            ' If startRow = 0 Then
            For x As Integer = 0 To dgvInventoryLog.Columns.Count - 1
                r.X = startX
                r.Y = startY
                r.Width = CInt(dgvInventoryLog.Columns(x).Width * percentage)
                r.Height = dgvInventoryLog.Rows(0).Height
                e.Graphics.DrawRectangle(Pens.Black, r)
                e.Graphics.DrawString(dgvInventoryLog.Columns(x).HeaderText, gridFont, Brushes.Black, r, sf)
                startX += r.Width
            Next

            startY += r.Height
            ' End If

            For y As Integer = startRow To dgvInventoryLog.Rows.Count - 1
                If y = dgvInventoryLog.NewRowIndex Then Continue For
                startX = e.MarginBounds.Left
                For x As Integer = 0 To dgvInventoryLog.Columns.Count - 1
                    r.X = startX
                    r.Y = startY
                    r.Width = CInt(dgvInventoryLog.Columns(x).Width * percentage)
                    r.Height = dgvInventoryLog.Rows(0).Height
                    e.Graphics.DrawRectangle(Pens.Black, r)
                    '  e.Graphics.DrawString(If(Not dgvInventoryLog.Rows(y).Cells(x).FormattedValue Is Nothing, dgvInventoryLog.Rows(y).Cells(x).Value.ToString, ""),
                    'gridFont, Brushes.Black, r, sf)
                    If x = 6 Then
                        Dim movementDate As Date = CType(dgvInventoryLog.Rows(y).Cells(x).Value, Date)
                        e.Graphics.DrawString(movementDate.ToString("dd/MM/yyyy"),
                                        gridFont, Brushes.Black, r, sf)
                        ' or dd/MM/yyyy
                    Else
                        e.Graphics.DrawString(If(Not dgvInventoryLog.Rows(y).Cells(x).Value Is Nothing, dgvInventoryLog.Rows(y).Cells(x).Value.ToString, ""),
                                        gridFont, Brushes.Black, r, sf)
                    End If
                    startX += r.Width
                Next
                startY += r.Height
                If startY >= e.MarginBounds.Bottom - 10 Then
                    If y < dgvInventoryLog.Rows.Count - 1 Then
                        e.HasMorePages = True
                        pageCounter += 1
                        startRow = y + 1
                        Exit For
                    End If
                End If
            Next
        Catch ex As Exception
            MessageBox.Show(ex.Message)
        End Try

    End Sub

this is the output

ps: im not that experience in stackoverflow(im always just copying code here and there) so if this is not where i should post question like this i will be grateful if you can direct me to the proper place.