[Koha] About word-phrase-utf.chr file

[Quoc Uy]

I'm trying to search for my language, using English alphabet. For example, when i type "a", Koha can search for "â, ă, á, ạ, ả".... (these are some alphabet in my language)

I'm now watching this file:
/etc/koha/zebradb/etc/word-phrase-utf.chr
I tried to edit this file, add some word to 
map "some alphabet in my language"  "some english alphabet"
but it didn't work.
Am i doing right thing? And can someone show me how to edit this file? I'm using Ubuntu 12.04.
Thanks so much!