What should I do after informing friends about the method of ghusl al-janabah? And is what I told them correct or not? And what should they do if it was incorrect?

This person has been greatly afflicted by waswas (obsessive whispering), so we advise him to ignore it and supplicate to Allah. Furthermore, there are two types of ghusl (ritual bath). If the ghusl that he informed his colleagues about included the sufficient ghusl, then their prayers are valid. Its validity does not depend on knowing whether it was a recommended or a sufficient ghusl. The important thing is that water reaches all parts of the body. We alert the questioner to the danger of issuing fatwas (religious edicts) without knowledge, and he must repent from that. He must also inform those whom he gave a fatwa to about the correct ruling, if possible.