There's a difference between wanting to know how to use a scanner, and wanted to know how to scan the local baby monitors. How ot avoid scanning them, sure. But how to scan them? That comes across like saying you want to know how to bug telephones, so you can make sure you don't accidentally do it.
But by all means, you tell me. What conceivable legal, moral, ethical, or laudable purpose do you have in listening in to local baby scanners, overhearing either wailing babies or private and perhaps intimate personal conversations? Maybe I'm just not seeing it, sure. Or maybe you're a PhD candidate doing some field research in the child-rearing habits of the local primates?
And of course, maybe you just hadn't heard, but unless you're really close to them, meaning, in the neighboring apartment or "patrolling" the streets, baby monitors are normally very low power transmitters. So you're not going to receive many of them--unless you're really trying to.