How do Wormholes form?

Wormholes may or may not exist, but if they did, here's how they'd work. In one universe or time period, there is a black hole. Then, in another universe, there is a white hole, which are the opposite of black holes. They shoot everything out into space, not sucking it in. So, you fall through the black hole and are ejected out the white hole, and you are in a parallel universe.