I don't have any code for connecting devices together, but you need to figure out how you want the "multiplayer" to work. Some multiplayer games connect to a specific server which handles pairing the two devices. Or you can connect one device directly to another device.
I've been trying to learn as much as I can about Android and through my research I came across a few sample applications and open source applications that would do what you want to do. I suggest spending a few hours searching for examples. Also, check out google code for android (open source projects). You can see what others have done to make multiplayer games.
Google Code Android