void PopulateColor(TreeNode node)
        {
            SqlCommand sqlQuery = new SqlCommand();
            sqlQuery.CommandText = "Select color,description From Cars where Cars.modelId in (Select IdModel from Models where nameModel = @modelName)";                
            sqlQuery.Parameters.Add("@modelName", SqlDbType.NVarChar).Value =
                node.Value;
            DataSet ResultSet = RunQuery(sqlQuery);
            if (ResultSet.Tables.Count > 0)
            {
                foreach (DataRow row in ResultSet.Tables[0].Rows)
                {
                    TreeNode NewNode = new
                        TreeNode(row["color"].ToString(), row["description"].ToString());
                    NewNode.PopulateOnDemand = true;                    
                    NewNode.Expanded = true;
                    NewNode.SelectAction = TreeNodeSelectAction.Expand;
                    node.ChildNodes.Add(NewNode);
                }
            }
        }