Assuming you have Find My iPhone enabled, you can open a browser on any computer go to
https://www.icloud.com and log in with your Apple ID, then click on Find My iPhone. That will show you a map where it is, if it has a data connection (WiFi or LTE or 3G) and battery life.
If you have a second iPhone on the same account, you can use the Find My iPhone App and it will show the same map, but with a dot also showing the second iPhone so you can see where it is in relation to you.
You can use the options in Find My iPhone to lock the phone, add a message to the screeen, erase the phone or make the phone play a sound to find it easier.