Why do you need dictionary? Try this and adapt:
List<string> cities = new List<string>();
cities.Add("New York");
cities.Add("Mumbai");
DataTable table = new DataTable();
table.Columns.Add("column1", typeof (string));
foreach (string str in cities)
{
DataRow row = table.NewRow();
row["column1"] = str;
table.Rows.Add(row);
}