What to backup so I can keep digitally signing with a gpg key pair

Hey so I’m new to the world of gpg/pgp. Using a test gpg key pair I created, the goal was to digitally sign a odf so I was wondering what do I backup so I could keep signing digitally using this key in case shit hits the fan and my computer no longer works? Using seahorse, I perfer it to the terminal, the options are to either...