In order to gain an understanding of what cryptocurrencies are and how they work, you better start by reading the relevant articles. Explore Blockchain technology and the concept of Bitcoin. If you do not want to invest your money and want to get Bitcoin for free, then you need to donate a certain amount of your personal time, for example, to collect a couple of thousand satoshi on Bitcoin faucets, and then, for example, start trading them. So you can easily get acquainted with Bitcoin and cryptocurrencies ecosystem.