Go to 'List all the available networks' from the first icon in the tool bar and it will give a list of IP addresses and select your local area network IP address and see all the communications between the computers inside your network with Internet and even you can see internal communication such as router and computer. Wireshark is simple but really useful tool that can be used to monitor all the activities inside a network as it happened.
You can actually use this for spy on other computers, Detect all the hidden communications between websites and your computer. Also this is a good tool for forensic investigations as you can detect internet activities in other computers without interacting with the computer.
