Step One:
Download and install "WiFi File Transfer" from the Google Play Store.
Step Two:
Make sure your Android smartphone or tablet is connected to the same network as your PC or laptop.
Step Three:
Launch the WiFi File Transfer app on your Android device. An icon should have been placed on your home screen by default.
Step Four:
Press the Start button.
Step Five:
Enter the IP address and port number displayed on your device into a web browser on your PC and laptop and hit enter.
Step Six:
If successful the browser will load the WiFi File Transfer interface. From here you can browse and manage your device's internal storage and SD card if it has one. You can both upload and download files between the two devices.