multiple value insertion in a single cell os grid view using checkbox

Question

hello,
checkboxes are in gridview.
when we select more than 1 checkbox, then their respective value move to another page's grid view.

following is the code for whcih i've to insert more than 1 value in a single cell of grid view.
each value is seperated with ","

foreach (GridViewRow row in GridView1.Rows)
        {
            CheckBox chkbx = (CheckBox)row.FindControl("CheckBox1");
            string Id = null;
        
            string hname = row.Cells[1].Text.ToString();
            for (int i = 0; i < GridView1.Rows.Count; i++)
            {
                if (chkbx.Checked)
                {
                    Id = Id + row.Cells[0].Text.ToString() + ",";
                    Response.Redirect("HotelMaster.aspx?m1=" + Id + "&m2=" + hname);
                }
             
            }

        }

what is wrong with this code..?
what will be the right code.
please help me to solve this problem..

thank you