2. Now type adb in a command shell will display all the options, adb.exe is SDK tool used to install applications and interface with the device.
3. Now Connect Your Android Phone to your computer using USB cable. You need to install Drivers for this. Download Android USB drivers from here. This driver is required for adb to interface with an android phone using USB cable.
4. Go to Android Settings/SD card & phone storage and disable Use for USB storage. You can enable it again later after you installed your third-party application.
5. Go to Settings/Application settings and enable Unknown sources.
6. Connect the G1 to your computer using the USB cable and install the driver you downloaded in step 3. After installing the driver you should see ADB Inteface in Windows Device Manager.
7. If you made it this far, download the APK file to a local folder on your computer, something like C:\MyAPKs will work fine and install it using ADB. The command would be adb install c:\myapks\ and that’s about it.
Anyway, the apk files refers to the Android Package files; and there are numbers of freeware you can try.