Youtube and Subtitles and Captions

A friend of a friend is profoundly deaf.
He was asking (thru my friend) about the Tube in general.
He was asking about captions.
I see with YT's last update you can add captions or subtitles to the videos.
I am stumped though with how to do it.
I did find a website where you can upload your videos ( or any video I suppose) and then add the text with their editing tool.
It did take a while but hey, it's raining and when i get my mind on something, it gets done.
The website is Overstream. It's worth a look until you/I can figure out YT's captions option.