Show data in datagridview by selecting multiple values from listbox c#

I want to show the data in datagridview by selecting multiple id's from Listbox in c# .

Here is my code

 private void listBox1_SelectedValueChanged(object sender, EventArgs e)
        {
            ListBox l = sender as ListBox;
            var selectedvalue = l.SelectedItem.ToString();
            this.BindData(selectedvalue);
        }

 private void BindData(string value)
        {
            DataTable dt= new DataTable();
            con.Open();
 SqlCommand storedProcCommand = new SqlCommand("spPOExport", con);
storedProcCommand.CommandType = CommandType.StoredProcedure;
            storedProcCommand.Parameters.AddWithValue("@BST_BESTELLUNG", value);
            SqlDataAdapter sda=new SqlDataAdapter(storedProcCommand);
            sda.Fill(dt);
            POGridview.DataSource = dt;
            con.Close();
        }

Any code or solution will be appreciated.

Thanks