How to do Paging, updating/edit and save data in datagridview

Private Sub MDIParent1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load  
Try
        
  conn = GetConnect()
            conn.Open()

            str = "select [DocId],[Description]      ,[Address]      ,[NoOfPages]      ,[SendOrReceived]      ,[SentDate]      ,[ReceivedDate]      ,[ForwardedWorkingUnit]      ,[Attachements]      ,[ForwardedDate]      ,[ReceivedBy]      ,[LetterWrittenDate]      ,[DocPath]  FROM [Data].[dbo].[mytable]ORDER BY Id DESC"

            com = New SqlCommand(str, conn)

            oledbda = New SqlDataAdapter(com)

            ds = New DataSet

            oledbda.Fill(ds, i, 20, "mytable")

            DataGridView1.DataSource = ds

            DataGridView1.DataMember = "mytable"

            conn.Close()

        Catch ex As Exception

            MsgBox(ex.Message)

        End Try
end sub

Private Sub Nextrecord_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Nextrecord.Click
        
        i = i + 20

        If i > 23 Then

            i = 18

        End If

        ds.Clear()

        oledbda.Fill(ds, i, 20, "mytable")
    End Sub

Private Sub PreviousRecord_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles PreviousRecord.Click
        
       i = i - 20

        If i <= 0 Then

            i = 0

        End If

        ds.Clear()

        oledbda.Fill(ds, i, 20, "mytable")

    End Sub