Help: how to use 'LONG' type?

I want to save a long string in a table, someone told me to use "LONG" type which is up to 2 gigabyte.
I tried like this:

       create table test_long ( id number,
                                content long);
       insert into test_long values(1,'xxx..........xxxxx')

but failed, if the string is more than 2000 byte, the error arises:
               ORA-01704: string literal too long