[Koha] Language Switch

Dear all, I was wondering how one can change the user interface. I figured there is an option that we can just switch once we added two PO files (the one we translating off-line). But I could not that option anwhere under Adnistrator screen nor OPAC one. If not, maybe it's wish-list that we can add for the next release. Please suggest if you already done so.. Thank you. -- Anousak (Anthony) Souphavanh "Small can make a big impact"