How do I register as a Barca fan?

Excuse me, I'm a passionate soccer enthusiast and I've been wanting to join the ranks of Barcelona's loyal fanbase. Could you please guide me through the process of registering as a Barca fan? I'm aware of the club's global fanbase and I'm eager to be a part of it. Could you elaborate on the steps I need to take to officially register? Are there any membership fees or requirements I should be aware of? Also, once I'm registered, what are some of the privileges and opportunities I'll get to enjoy as a Barca fan? Thank you for your assistance in this matter.