keep your emulator up and running. In the command line, go inside the platform-tools folder, in your sdk folder which come with adt bundle and execute following command :
>adb install <yourFilename.apk>
This command detect your running emulator/emulators and show you the list of devices where you can install this app(show if any physical device/devices connected to your computer.). Then you can select any one, if only one emulator is running then app will directly installed on it by default.
Note: For above command your .apk file needs to be in same directory.
for more detailed tutorial follo : This link