I think the glitch is that you want to read or watch it somewhere and then use it right away. Imho I'd do this:
1 - Buy at least 4 octave midi keyboard, if you don't have already. They're not too expansive.
2 - Load any listenable piano plugin.
3 - Slap a long reverb on it (like 30% w/d) so you'll enjoy it a bit more.
4 - Try what sounds good and what not. Combinations of notes. Pressed at once, then pressed after each other. Little melodies will appear that you can enjoy and try to develop. Trial and error will show you what works and what not.
5 - Cross reference those "rules" you've found with those books/videos you try to digest right now. You'll find out that you've discovered different intervals, chords and scales all by yourself. That book will name it for you.
6 - Try to keep this as a good time, not as a mandatory unpleasant learning experience.