I don't really know much about Translation jobs yet, but as far as I know the file or the things that you will need to translate actually depends on the OP actually. It could be a website or a doc file or whatever it is they want translated to a certain language. And yes, what the previous guy said, making a portfolio is a pretty good idea if you want to start. It's a good thing as well if you have proof that you can actually do the job and translate things to a language that you're good at. Hope this helps