A DataSet holds one or more DataTables.
Example 1:
DataTable dt = new DataTable();
DataSet ds = new DataSet();
ds.Tables.Add(dt);
Example 2:
DataTable dt1 = new DataTable();
DataTable dt2 = new DataTable();
DataSet ds = new DataSet();
ds.Tables.Add(dt1);
ds.Tables.Add(dt2);
If you want any more, then do your own homework.