How can i use listDictionary like list generic?

Question

How can i use ListDictionary like List my sample codes below real codes is last one.

 for (int i = 0; i < listMyColumnNames.Count; )
            {

                if (i < listMyColumnNames.Count - 1) ---> this is important
                    Text += ", ";
                i++;
            }

how can i do with ListDictionary.

  int QuantityInt;
            double QuantityDouble;
            ListDictionary ld = new ListDictionary();
            foreach (DataColumn dc in dTable.Columns)
                ld.Add(dc.ColumnName, dTable.Rows[0][dc].ToString());

            foreach (string ky in ld.Keys)
                if (int.TryParse(ld[ky].ToString(), out QuantityInt))
                    ld[ky] = "integer";
                else if(double.TryParse(ld[ky].ToString(), out QuantityDouble)
                    ld[ky]="double";
                else
                    ld[ky]="nvarchar";

  void CreatSqlTable(ListDictionary ldColumns ,List<string> listMyColumnNames, string TableName, string MaxCharacterValue)
        {
            string Text = "Create table ENG_" + TableName + " (ENG_" + TableName + "_ID integer PRIMARY KEY identity(1,1), ";

            for (int i = 0; i < listMyColumnNames.Count; )
            {
                Text += "[ENG_" + TableName + "_" + listMyColumnNames[i].Replace(' ', '_').Replace("_-_", "_").ToUpper(CultureInfo.InvariantCulture)+ "]  nvarchar("+MaxCharacterValue+") ";
                if (i < listMyColumnNames.Count - 1)
                    Text += ", ";
                i++;
            }