On your Mac, go to the menu bar and next to the clock, you will have a small B character symbolizing the Bluetooth feature. Alternatively you can go to System Preferences > Wireless Communication > Bluetooth.
Activate the Bluetooth. The symbol changes from light gray to black.
Click it again and choose "Send file ..."
Choose the file and click on the Send button.
All the nearby Bluetooth devices should have already been detected during the scan.(gray rotating wheel).
Select the Device of your choice and transfer the file.