While the title might lead you to think this is an elementary book on prayer, I found that not to be the case. It's really more a survey of everything he's learned about prayer over 32 years as a priest, after studying the subject, doing it, going on retreats, pilgrimages, and talking to people about the subject.
He's a Jesuit priest so his perspective is a little different than the Protestant perspective.
The book is a quite comprehensive survey of different prayer techniques, and illustrations of those techniques.
It's a good book where you will likely learn some techniques for prayer you didn't know before.