How to make datadridview refresh

private DataTable items = new DataTable();
 /// <summary>
 /// Called once when form displayed for first time
 /// </summary>
 /// <param name="sender"></param>
 /// <param name="e"></param>
 private void FrmMain_Shown(object sender, EventArgs e)
     {
     items.Columns.Add("URL");
     items.Columns.Add("Name");
     items.Rows.Add("https://www.codeproject.com/", "CodeProject");
     myDataGridView.DataSource = items;
     }
 private void AddARow_Click(object sender, EventArgs e)
     {
     items.Rows.Add("A new URL", "A new name");
     }