As you can see, information about different layers of TCP/IP Protocol is listed. Selecting a packet would show many information about that packet. Now you can click on a packet to select it. I pinged from the terminal and as you can see, many packets were captured. I am capturing packets on the ens33 wired network interface as you can see in the screenshot below. Just press and hold and click on the interfaces that you want to capture packets to and from and then click on the Start capturing packets icon as marked in the screenshot below. You can also capture packets to and from multiple interfaces at the same time.

You can also double click on the interface that you want to capture packets to and from to start capturing packets on that particular interface. Now to start capturing packets, just select the interface (in my case interface ens33) and click on the Start capturing packets icon as marked in the screenshot below. Here, I listed only the Wired network interfaces. You can choose to show specific types of interfaces in the welcome screen from the marked section of the screenshot below. There are many types of interfaces you can monitor using Wireshark, for example, Wired, Wireless, USB and many external devices.

When you start Wireshark, you will see a list of interfaces that you can capture packets to and from.

How to install wireshark from terminal