Using the explorer or finder tool for your operating system, navigate to the /sdk/extras/google/play_billing where is replaced by the path into which you installed the Android SDK. From this location, copy the IInAppBillingService.aidl file, return to Android Studio and paste the file onto the com.android.vending.billing package in the Project tool window. In the Copy dialog, accept the default settings and click on the OK button. At this point the relevant sections of the Project tool window should be organized to match that of Figure 56-3: