There are many programs dedicated for this job. Subtile Workshop, Subtitle Translator are some of the best.
As for notepad (J7N - half of my friends use it to create subtitle) the way to transform in frmes goes like this:
A 25 fps movie
the time is: 10 min 25 sec
the frame is: (10 min X 60 secs + 25 secs)*25 fps=15625 frames
In short: multiply the number of the seconds with the framerate and you should have the frame number.
On the other hand, in Notepad it's easyer to work with srt format, that it's based on time and not on frames.
