How to find your iphone with find my iphone app?

I have the app installed on my iphone but my iphone is offline. I have my mac with me which is online. How does find my iphone work? I have it locked and the display message says to call me at a different number when found. Do I get an email or phone call when someone is trying to use it though?

Put it in lost mode if you lost it, if off you can't see where its at on a map but you can prevent anyone else from using it. It will mark its last spot when its turned on.