I know you are concerned about where to start... just remember if you don't help her she will be gone ... i suggest this video to help you gain confidence...

Repot video...

https://www.youtube.com/watch?v=P1e0PZOXOz4&list=PL5BPiSTiIruZQaLczwvIX-umYRYHKsOqN&index=2&t=177s

also get a orchid pot liner see link...

https://www.amazon.com/s?k=orchid+pot&crid=2XEEC8CKOYSZ7&sprefix=orch%2Caps%2C80&ref=nb_sb_ss_i_1_4

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orchid mix link...

https://www.amazon.com/Purpose-Orchiata-Monterey-Imperial-Orchid/dp/B00D73XSCY/ref=sr\_1\_1\_sspa?keywords=orchid+mix+for+repotting+big+chunks&qid=1649430714&sr=8-1-spons&psc=1&smid=AG8OLTMV8PYLY&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUFMNzI2WllYWU5ZUEEmZW5jcnlwdGVkSWQ9QTAwNTEzMzUzVVlMVFRXWVhVSVczJmVuY3J5cHRlZEFkSWQ9QTA2MjQ0MTgyVEtONTJIVkFBRzJaJndpZGdldE5hbWU9c3BfYXRmJmFjdGlvbj1jbGlja1JlZGlyZWN0JmRvTm90TG9nQ2xpY2s9dHJ1ZQ==