To use an APK file on your device, the first thing you should do is allow installation from unknown sources in your Android settings. Later, you can download the APK file, find the file using a file manager, and then tap it for installation. To install the app, follow the prompts that appear on the screen. After the installation, you will be able to open the app as usual. If you are trying to launch APK files on a non-Android device, they will not run without using an emulator or other special tools.