How do I buy from GOG?

Excuse me, could you please elaborate on the process of purchasing from GOG? I'm quite new to this and am not sure where to start. Do I need to create an account first? Are there any specific steps I should follow to ensure a smooth transaction? Are there any payment methods that are preferred or not accepted? Additionally, are there any fees associated with buying from GOG that I should be aware of? Lastly, how can I track the status of my order once it's been placed? Thank you for your assistance.