You could just use the Steam browser.
You can do that from ingame assuming you have the app online...
I don't think this is what he's looking for. He wants to be able to have one screen for the game and another to use as he wishes, for stuff like notes among other stuff.
As far as I know, the only way to do it is to put the game into windowed mode, drag it to the monitor you want, remove the borders, and set the resolution of the game to that of the monitor you want it on.