There is nothing confusing about it but a straightforward process. First thing would be to know your country's perspective on crypto and the exchanges that are supported, let's assume it is Binance exchange. Assuming it is Binance exchange, you visit Binance exchange and create an account, since you want to purchase with fiat, it means you will have to get your account verified, that is, submitting some documents like your Identity Card, after the account is verified you can buy Bitcoin with your credit card. This is just an explanation with Binance exchange and same or almost same steps with other exchanges that are supported in your country.