Does your computer have bluetooth on it? If it does, then you should be able to turn on the bluetooth on your computer and add your phone as a device.
When your phone is set up as a device, click to send the image via bluetooth and find your computer. Select it and your computer might ask for a pin number to be created, enter 0000 or something easy, your phone might then ask for the pin number, so type 0000 again or whatever you typed before.
The phone should then begin to send the image to your computer.
If all goes well, your image might be stored under your documents in a folder called Bluetooth received files.