There may be others more familiar with this. I have a MacBook Pro, but I actually download using windows in emulation.
I just connected it though, and here is the method I used:
Go to settings. (Adjust button)
Scroll down to the 'usb class COM' item. (Start button = Up Reset button = down)
Press Adjust and Change it to 'USB class UMS'
Scroll down one place to 'USB MSC'
Connect cable
Press Adjust again and it should show that it is connected in the watch.
Wait a minute or so for the drive to appear on the desktop.
Double click on it to open.
Drag GPSLOG.SBP in it onto your desktop.
One more vital step: click in the GPSLOG.SBP file and 'get info'
Now untick the 'locked' box so you can open the file and save it.
Give the file a date and save it.
Analyse in you favourite program. Done.

Hope this helps.