Android phones come with Google paly installed on them. When you first access to Google play then Android Device manager will get installed directly on your smartphone.
First you need to activate ADM in your mobile.
How to Activate Android Device Manager
To activate ADM in your device
Go to Settings then move on to Security After that Device administrators. There you will see Android device manager option, tap on it to activate.
Settings →Security → Device Administrators →Android device manager
Once Android Device manager is activated on your Mobile, Open your browser and follow these simple steps
Now Go to Google Play. There you will see a Gear Icon at the top right corner.
Click on that Gear Icon and select Android Device manager from the drop down list.
After clicking on Android device manager you need to sign with your Google account that you are using on your android device.Once Android Device Manager finds your phone, it will show the Location of your phone using Google Maps. It also gives the distance that it is away from you.