Do you have a wireless card on your computer and are you within range of his network? If yes to both of those then it should auto detect the network and, if it's not secure(probably isn't) you can now browse around.
Next you have to see if you can access his files from the network, which I also doubt.
Go to my network places>computers on network
It's not that exactly, but you'll figure it out. Then browse around his computer and find the file.
If that doesn't work then try and break into his house . . .