approve/reject through dropdownlist.

previously i try to approve /reject thrugh buttons and i try to code it but now i try to approve/reject through dropdownlist but i dont know how i code though dropdownlist....

this is code when i add buttons of approve and reject..

    protected void GrdFileApprove_RowCommand(object sender, GridViewCommandEventArgs e)
    {
    if (e.CommandName == "_Approve")
    {
    //using (SqlConnection con = DataAccess.GetConnected())
    using (SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["mydms"].ConnectionString))
    {
    try
    {
    con.Open();
    int rowindex = Convert.ToInt32(e.CommandArgument);
    GridViewRow row = (GridViewRow)((Control)e.CommandSource).NamingContainer;
    Button Prove_Button = (Button)row.FindControl("BtnApprove");
    SqlCommand cmd = new SqlCommand("approveee", con);
    //cmd.CommandType = CommandType.StoredProcedure;
    cmd.CommandType = CommandType.StoredProcedure;
    //con.Execute("approve", new { UserID, DocID, ApproveID });
    cmd.Parameters.Add(new SqlParameter("@UserID", UserID));
    cmd.Parameters.Add(new SqlParameter("@DocID", DocID));
    //cmd.Parameters.Add("ApproveID", (object)ApproveID ?? DBNull.Value);
    cmd.Parameters.Add(new SqlParameter("@ApproveID", ApproveID));
    int result = cmd.ExecuteNonQuery();
    if (result != 0)
    {
    GrdFileApprove.DataBind();
    }
    }
    catch
    {
    apfi.Text = "Not Approve";
    }
    finally
    {
    con.Close();
    }
    }
    }
    else if (e.CommandName == "_Reject")
    {
    using (SqlConnection con = new SqlConnection(ConfigurationManager.ConnectionStrings["mydms"].ConnectionString))
    {
    try
    {
    con.Open();
    int rowindex = Convert.ToInt32(e.CommandArgument);
    GridViewRow row = (GridViewRow)((Control)e.CommandSource).NamingContainer;
    LinkButton Prove_Button = (LinkButton)row.FindControl("Button1");
    SqlCommand cmd = new SqlCommand("sprejectapprove", con);
    cmd.CommandType = CommandType.StoredProcedure;
    cmd.Parameters.Add(new SqlParameter("@UserID",UserID));
    cmd.Parameters.Add(new SqlParameter("@DocID", DocID));
    cmd.Parameters.Add(new SqlParameter("@ApproveID", ApproveID));
    int result = cmd.ExecuteNonQuery();
    if (result != 0)
    {
    GrdFileApprove.DataBind();
    }
    }
    catch
    {
    apfi.Text = "Rejct";
    }
    finally
    {
    con.Close();
    }
    }
    }
    }

plzz can any one tell me how i done with dropdownlist?