I read a series of books a few years back.

It was about a boy upon finishing school decides to apply to an ad about a job. The ad states wizards apprentice, no illusions. Real magic.

As he arrives he reads a book in the waiting room about magic. Then walks through the door to the interview room, this door is the portal.

He starts learn about magic from the book as he explores. He is soon attacked by wolf's and saved by an archer.  This archer takes him to a village that becomes his home.

In aiding the town he rids an old house i believe of some magical/ghostly shirt.

He gains skill fast, gains a home and enlists a younger boy who due to a magical amulet ages fast and becomes a skilled warrior.

In the end, he establishes a religion. That the younger boy becomes the leader of at the end.