I have a simple \"Hello Android\" application on my computer (Eclipse environment), and I have built an APK file. How do I transfer the APK file to my Android phone for test
Directly connect your Android device and select the USB debugging option in the device. Eclipse will itself find your device, and then just run the code.
Or alternatively, paste your APK file in the Android SDK platform-tools folder and from the command prompt install it like this:
D:......../platform-tools> adb install yourfile.apk.