How do you pay for Gog games?

Excuse me, I'm interested in purchasing some games from the Gog platform. Can you please walk me through the process of how to pay for them? Do they accept a variety of payment methods, such as credit cards, debit cards, or even cryptocurrencies? Is there a specific step-by-step guide I can follow to ensure a smooth and secure transaction? Additionally, are there any fees associated with making purchases on Gog that I should be aware of? I'd appreciate any insight you can provide to help me navigate this process.