chinese charset always be showing with '????' in a query

I installed a oracle database at my Win7 laptop.

Currently, my oracle database has below information:

select tab1.aa||'_'||tab2.bb||'.'||tab3.cc from

(select VALUE$ aa from sys.props$ where name='NLS_LANGUAGE')tab1,

(select VALUE$ bb from sys.props$ where name='NLS_ISO_CURRENCY')tab2,

(select VALUE$ cc from sys.props$ where name='NLS_CHARACTERSET')tab3;

It returns "AMERICAN_AMERICA.WE8MSWIN1252".

My Win7 is a English version. No any chinese charset installed.

I access register: HKEY_LOCAL_MACHINE->SOFTWARE->ORACLE->HOME   NLS_LANG=AMERICAN_AMERICA.WE8MSWIN1252

I create a table and insert some chinese at its columns. But I always get "????" at these columns after query.