Dude, please use the search button. This has been discussed dozens of times. Here is the original post by Uli talking about his exercise.
(NOTE: In his post Uli says “meatus,” which is the opening for urine at the end of the glans, when he meant “corona” or the largest part of the glans.)
You’ve asked this question twice before: one and two. Please don’t start duplicate threads when your question has already been answered.
However, since I’ve gotten this far:
Your grip at the base should be tight enough to prevent blood from leaving the shaft. Your strokes should be tight and short, not all the way to the end. If you’re squeezing hard enough at the base, you won’t want to make strokes longer than about an inch because of the build up in pressure. How many? Keep it simple at first. Five or six. Let your dick get used to the pressure.