To create a partitioned table from an existing table, use the select into command.
You can use select with the into_clause to create range-, hash-, list-, or round-robin–partitioned tables. The table from which you select can be partitioned or unpartitioned. See the Reference Manual: Commands.
select * into sales_report partition by range (qty) (smallorder values <= (500) on seg1, bigorder values <= (5000) on seg2) from salesdetail