Whenever there is a vacancy for Professors at Hogwarts,a notice is put up on the bulletin boards in the newsroom inviting people to join in as professors at Hogwarts.For further details on the process,you need to tap the notice with your wand to unfold and read the entire parchment notice.

Professor Assistants or PAs are volunteer students who excel in their studies and choose to help Professors grade assignments submitted by their students.Whenever applications for the post of Professor Assistant,are invited,a notice is put up in the newsroom,which can be tapped with a wand and read for further details.

You can also find notices for Professor Applications and Professor Assistant Applications,beside the Donation box,in the volunteering section at Hogwarts castle,where you are invited to volunteer as staff for the Hogwarts administration or as Professors and Professor assistants.