Yea its tough, like he said just reading it won't change anything. I'm still the same person today as i was yesterday reading it, perhaps a little bit wiser but no more socially adept.
Reading the book is a good first step, so congrats on that. However like he said beating social anxiety is more about lowering your inhibitions and fears rather than adding something to your personality. In that sense its more about persistence and habit than learning anything new.
Rome wasn't built in a day...it will take many hard fought months or years and persistent exposure to uncomfortable social situations to be free of anxiety.
Good thing is, you know what to do now, you just have to do it, over and over again until your brain knows it too.