Import a game from somewhere else I'm guessing?
Find something called a PGN and upload it via the TOOLS "Import a game" button
It looks like this:
[Event "Rated Rapid game"]
[Site "
lichess.org/Z01xx8LK"]
[Date "2021.10.11"]
[White "Reini"]
[Black "IloveAnya"]
[Result "1-0"]
[UTCDate "2021.10.11"]
[UTCTime "16:37:09"]
[WhiteElo "1894"]
[BlackElo "2010"]
[WhiteRatingDiff "+8"]
[BlackRatingDiff "-31"]
[Variant "Standard"]
[TimeControl "600+0"]
[ECO "A09"]
[Opening "Réti Opening: Réti Accepted"]
[Termination "Normal"]
[Annotator "
lichess.org"]
1. Nf3 d5 2. c4 dxc4 { A09 Réti Opening: Réti Accepted } 3. e4 b5 4. a4 c6 5. axb5 cxb5 6. Na3 Qb6 7. d4 e6 8. Be3 Bb4+ 9. Nd2 Qb7 10. Be2 a6 11. Bf3 Qd7 12. O-O Ne7 13. Ndxc4 bxc4 14. Nxc4 Qd8 15. e5 Nd5 16. Bxd5 Qxd5 17. Nb6 Qb7 18. Nxa8 Qxa8 19. Qa4+ Nc6 20. Rac1 Bd7 21. Rc4 Be7 22. Rfc1 Nxe5 23. Rc8+ Bd8 24. Rxa8 Bxa4 25. Rcc8 Ke7 26. dxe5 Bd7 27. Bc5+ Ke8 28. Rxd8# { White wins by checkmate. } 1-0
Also if this game you want saved is played on lichess theres a FEN&PGN button at the bottom screen when you go into analysis.