This is more like notes on how to use Wireshark so probably won't find a very in depth discussion but hopefully enough to get you going.
You should have wireshark already installed.
On the menu, click Capture - Options
Click the name of an interface under Interface List to start capturing packets on that interface. For example, if you want to capture traffic on the wireless network, click your wireless interface.
As soon as you click Start, you’ll see the packets start to appear in real time. Wireshark captures each packet sent to or from your system. If you’re capturing on a wireless interface and have promiscuous mode enabled in your capture options, you’ll also see other the other packets on the network.