Hi devusha,
Well, in this case you add a column manually like:
dt1.Columns.Add("newColumnName",Type.GetType("String"));
and If you want to copy this column to another datatable, you can do like this:
DataTable dt2 = new DataTable();
dt2.Columns.Add(dt1.Columns["newColumnName"]);
Hope this helps!
Happy Coding:)
Best Regards,
Sunny K