You go into the control pannel and select Network and Internet and then select Homegroup and then select Print and view the network password. You can print it out if you want and keep it someplace or just write it down.
You went into the homegroup and saw what the homegroup password was ? That is the password that the other computers need to get on by wireless. The password to get into the router and the homegroup password are two different passwords.
1)Open the web browser that you use: Firefox,Google Chrome,IE,or Opera and type in the IP address for your router,and press the Enter key. http://www.routeripaddress.com/< Router ip addresses can be found here
2)A window will open and then type in your routers default username and password,and press the Enter key again http://www.routerpasswords.com/< Router usernames and passwords found here
3)Navigate to the Wireless Security\Network Security Settings Tab and open it to locate or change your WEP or WPA Security Passphrase. Use WPA because it provides better security.
4)Write this Security Passphrase down and put it in a safe place to access when needed.
You go into the control pannel and select Network and Internet and your next page you should see the wireless network that you have set up , if you don't then you need to set up a wireless home network. You can't just buy a router and think you will then just start connecting devices to it , you need to set up a home network and once you do you will see that it's called a homegroup.