By far the easiest subtitle files to work with are the .SRT files. They can be manipulated in a regular text file editor. I would suggest that you find a subtitle site like opensubtitles.org, download a subtitle in the .srt format and use google translate to do the translations. Even when a film is not released for the international market, often a subtitle is created for the hard of hearing in the local market. There are a few steps to remember to make sure the file will work.
Translate the text. (Google will only translate reliably for the first 300-400 lines of subtitles. You might have to break the translation into smaller pieces.)
There is a special symbol used in .srt files to indicate the length of time a title remains visible on the screen. That character is --> (minus, minus,Greater than) and google translate misses the second - (minus). Perform a 'Find and Replace' and change every -> with -->.
Google Translate often adds a space after the colon in the time field, so use 'Find and Replace" again and replace ": " (colon,space) with ":" (colon).
Save the text file using "Save as.." making sure that the file ends with the .srt extension
In order for the video player to automatically open the subtitle file, make sure the the .srt file HAS THE EXACT NAME AS THE VIDEO FILE. So if your video is called "123 The Happiest Pink Pony and Me.avi" the subtitle .srt file must also be named "123 The Happiest Pink Pony and Me.srt", (remember the .srt extension).