How can i get onto my brothers minecraft server by a computer to computer connection?

my brother finally got a server up and we are trying to avoid the port forwarding crap so i thought i could set up a homegroup thingy and since through that i can acces with computer files can't i just connect? but no the group has no internet acces and I'm not sure that's the problem or if I'm just doing the wrong thing. please help I'm so confused!