How do I activate Guild Wars 1?

Could you please provide a step-by-step guide on how to activate "Guild Wars 1"? I've recently purchased the game but I'm a bit confused about the activation process. I've heard that it involves creating an account, downloading the game, and then entering a unique code. However, I'm not sure where to find this code or how to proceed from there. Any assistance you could offer would be greatly appreciated. I'm looking for a clear and concise explanation that will help me navigate the activation process smoothly.