Also, to simply start today, download Bitcoin Core into your computer.

That's basically the original software that Satoshi developed, it's free, runs in any device you already have.

Create a wallet there, learn how to use wallets, bitcoin transfers, etc.

Then continue from there. Or don't. That's up to you. The early retirement by bitcoin guy just uses that.

It's not perfect, it can be done much better, but it works, and it's better than having your coins in an exchange.