As a regular CTF competitor for over 4 years now, I cannot emphasize the value in simply playing CTFs if you really want to learn this stuff. So many people seem to think there's a secret manual laying around that teaches you all that is involved in going from a compiled binary to a shell. The referenced book should be used as a resource for when you come across a new topic and need some help. If you want to get started here are some useful links.

http://smashthestack.org/

https://ctftime.org/

http://overthewire.org/wargames/

http://repo.shell-storm.org/CTF/

https://github.com/ctfs/write-ups

Or is it more relevant to say "this is HOW I want to learn"? I'd contend that one of the best ways for a person to learn about technology / engineering /computing / ... is to open things up and see how they work.

It's an especially good way for teenagers to learn, before they get bogged down in the exam regime of the later years of high school, as they have insatiable curiosity and a seemingly infinite amount of time. In the hands of a curious teenager, a smart phone and an open-ended mandate to break it, could be a pocket sized, multi-year course in nearly every aspect of electronics and programming.