Do you want them hard-coded or do you want people to be able to turn them off?
If hard-coded is all you need, then you can use your editing software to add the text onto the image. If you want people to be able to turn them off, you'll need to create an .srt file. There are some free programs out there. From what I understand, you will need to go line by line and tell the program what timecode the text should start and stop. Then you generate an .srt file, put it in the same folder as your video file and name it the same as the video. When you play the video it will automatically load the .srt file and you'll have the option to turn it off through the subtitles menu options.