How did you learn about fundamentals of stock market investing ?

How did you learn about fundamentals of stock market investing ?

How did you learn about fundamentals of stock market investing ?

This question has been asked so many times already so I apologize for asking again.

So how did you learn about fundamentals of stock market investing ?

I am open to learning from books or YouTube.

I already invest in index funds.

I want to invest in individual stocks as well. And learn how to pick stocks for long term and/or dividends.

I am not planning to do day trading.