add comment to table creation script(urgent)

Hi, all
How do I add a comment to a table creation script after the table has been created. I tried
SQL> alter table TABLENAME add comment on ....
and it did not work. Any help would be appreciated.

dragon

COMMENT ON TABLE schema.table_name IS
'This table holds attributes of a product.';

COMMENT ON TABLE tablename 'YOUR COMMENTS';

Thanks for timely response.

Sukimac is correct.

Sorry missed 'IS'

Raghu

I am sorry I did not make clear before, my developer wants to put comment on column, I need the syntax for comment on column not just on table. Thanks again for help.

COMMENT ON COLUMN tablename.columnname IS 'your comment';

Thanks to all!