I've found that getting a wallet and sending some Bitcoin is a great first step. This course introduces Bitcoin and also surveys an array of other decentralized, blockchain projects: https://www.pluralsight.com/courses/bitcoin-decentralized-te... (caveats: self-promotion, pay-walled, but the free trial allows you to watch 95% of it).

Bear in mind that the word "blockchain" is an evolving word; almost every definition I've read differs. Some see it as barely different than a distributed database that doesn't allow deletions. Many others see it as paradigm shifting.