New here, any advice?

Hey all,

I just purchased a YubiKey 5C NFC device . I’m mainly interested in using it to secure my Gmail and my Strike for Bitcoin account.

Any advice how to set this up properly? I’m a totally newbie so if there are other threads on this please point me to them.

I do understand I should purchase a second device in the event I misplace my primary one. How would that work? Can I set up two keys to both have access to the accounts it’s linked to?

Any advice would be appreciated. Thanks!