FINALLY, I get the replied (from myself)....! I have to install the 3rd party software (nova pro) to make the backup worked; actually, this software is included on the linkstation BUT it is NOT written anywhere on manual or guide..etc..
Now, i can back up my local drive/etc..into my nas. I can open, write, drag...etc..from office or other place into my nas at home by installing buffalo web access into remote machines BUT i don't know or I couldn't find the way to automatically backup my remote machines into my nas at home. Any help please.....................................!