1. Put your phone in "Discoverable" mode.
2. Open your MacBook's Bluetooth menu and search for devices.
3. When your phone appears on the list, connect. It will ask for a PIN, just
enter "0000".
4. Your phone will ask you if you want to pair with your MacBook. Accept it, and enter the "0000" pin again.
5. The phone and the MacBook should then ask something similar to "Do you want to automatically accept pairing requests from (device name), or always ask?" Choose "Always connect" or whatever it says.
6. Then, go in to your phone's Bluetooth menu and try to send the file to the MacBook again. If it still can't send the file, it's the phone, not the MacBook.