Both running windows 7?
I am not sure by your description what is the exact problem.
Try to describe in details what you want to do what exactly you did, and what was the outcome.
In any case, just for testing disable the firewall. And i recommend using advanced file shearing
In my opinion, it's best to ignore the Homegroup method of networking in Windows 7 and stick to the more conventional way of just joining a Workgroup. Further down the left hand pane in the Network and Sharing Centre - below the Homegroup option, it says Networking and that's the way to go.
In there you can change the option to have all the machines use a password - select that one, make sure all the systems are in the same named Workgroup and off you go.