maybe you can try the indonesian embassy.. if you're lucky, they might have a course for bahasa indonesia (not sure about this one). perhaps they can provide/suggest you some contacts who would provide indonesian course.. who knows..
or just try to interact with as many indonesian as possible (not saying bahasa indonesia is the easiest, it has its own complication. but grammatical-wise, it's pretty easy.) or maybe you can try conversation exchange website.