Defining non English languange as a default

Hi everyone i browse the net yesterday then i take look a shopping cart named opencart  then i dwload it unzipped to my local webserver give it a try and i also dwload the indonesian languange pack. The question is how i can make the indonesian languange as my default languange. I don't need English language pack only the indonesian. The problem is when i try to get rid of it i got error message claimng that currency is unknown. Can anybody help me out?
Thanx