Running your app from an emulator is pretty easy. Click on the play icon on the Android Studio toolbar, as shown in the following screenshot:

On the Select Deployment Target screen that pops up, select the device you want to run the app on and click OK:

Android Studio will build and run your app on the emulator:

If you do not already have an emulator running, your emulators will show up under the Available Virtual Devices section. Selecting them will start the emulator and then run your app on it: