Firstly, what Operating System are you using? This would help us to guide you through a specific process.
However, to put it all bluntly, you need to turn on "Network Discovery" which will enable any computers on the network to see each other.
If you then go to 'Network and Sharing Center' and click your network you should see any other devices/computers on the network, assuming you don't have a firewall which blocks them.
Then, you will need to enable file and printer sharing, with or without password, public folder sharing and/or media sharing.
It's all done within 'Network and Sharing Center'...