How to convert ANSI into UTF-8 ?

Does anybody know, how to convert ANSI encoding into UTF-8 as we want to implement languages such as russia, japanese, … into a website. We have to have displayed both standard ANSI charset (english, german, ….) and UTF-8 (japan, russia, …). The only possible way is to encode the whole site in UTF-8. Does anybode know how we should convert our ANSI listinge into UTF-8 ?