Do you know a guide somewhere where I can learn how to play Mahjong?

Here is a quick You Tube video on how to.
https://youtu.be/kPmCb80AWYg

I actually bought a book on how to play it and had no idea what they were talking about. So I’m either stupid, senile or both.

I play an app on my phone. It’s fun. Probably harder in real life to master though.
But I have never played the real life version

I played the real (not on a computer) game a lot as a child, and this Wikipedia explanation of rules and game play is the closest as to what I remember. In its basic form, it is similar to playing rummy.
I hope you are going to play with real tiles with your friends, it’s a terrific game!

Keep in mind that there are several variations of this game.
Another way to learn, after you sort of know the basic rules, is to go a senior center with a large Chinese population. First ask if you can just observe, because you want to learn. Then as you get to know the people there better, ask if someone is willing to teach you as you play along. Ask if there are beginners’ groups.
I understand that it is a social game, so getting to know the people is part of the fun.

Search “how to play mahjong” on YouTube to learn the rule first and then find some Chinese neighbors to practice. By the way, they are pretty good at it. And I was heard that their grandchildren could play mahjong since 6 years old!

Check your local community/rec center. Maybe they could host a Mahjong night/day. You’d be able to find people that love mahjong as much as you, then you will always have that extra helpfulness, in person though.