First, as always, enable Bluetooth. On a Windows 10 machine, open the Start menu, click the cog icon to launch the main Settings pane, pick Devices > Bluetooth & other devices, and switch on Bluetooth. To actually share the file, you'll have to connect the sending device to the receiving one. From the same Bluetooth & other devices screen, hit Add Bluetooth or other device > Bluetooth to search for another Bluetooth-enabled Windows or Android machine. When the device you're looking for appears, tap or click it to connect. Now that your devices are successfully talking to each other, stay on the Bluetooth & other devices page and click Send or receive files via Bluetooth on the right side of the screen. Choose Send files, then the device you want to beam them to, and hit Next. On the subsequent screen, click Browse to search through your files, tap the one you want, and select Next once more to confirm.