Host unity game with photon

I don't understand basic thing: how to make multiplayer game work online on server not on my pc? In the case we use photon and photon cloud? what is purpose of photon cloud when I need to save game on other machine? how to do that? If I want 100 free CCU photon and to use photon cloud how will I do it...

When using photon cloud where my game has to be saved/hosted? And what is basic scenario my game has to be started on server and clients will join...? how to get all things work???