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
good Luck!
