How to know the hidden meanings in Surah Al-Fatiha for curing illness?

I've read a hadith(authentic) where a companion **healed another person by reciting Fatiha.** It's also recited among the Salaf for healing purposes. But one needs to know the subtle meanings of this surah & what it contains of to properly avail its healing ability(obv all healing comes from Allah SWT, everything else just a medium). Source: Zad Al-Ma`ad 4/318 So, how do I come to know these **subtle meanings & insights from the Surah Al-Fatiha?**