Custom subtitles to DVD

I have an educational DVD with REG speech I want to write to English subtitles. The end result will therefore be an English subtitled film with that speech. There is no text file to download on any website, I have to write myself. (Phew!)

How should I go about? What programs do I need, and how do I create text and then get the text with video. Do you have any tips, there are free-ware to use. I found a couple of guides on videohelp.com but they were from the -05 and -03. There might be better / simpler program now.

Grateful for your help. I am quite a novice in the field.

http://tmpgenc.pegasys-inc.com/en/product/te4xp.html

This is not their own texts but it is excellent to do so.

http://subtitle-workshop.en.softonic.com/

Subtitle workshop is well-known law. Further down the page are 3 other programs. My own experience is minimal. But there are manual in the program for help. Is also a recent Beta version of subtitle workshop.

Thanks for the tips. I will now I play a bit this weekend.