This is where it gets tricky. In order to find this icon, you have to find the character selection screen (There is a guide here to help you with this)

After you located the character selection screen. Proceed to step 2.

This is the hard part, only experienced PC Gamers know how to complete what is known as a "Left-Click" in the industry.

Once you've googled how to "left-click" or your little brother showed you how, you can now proceed to move your mouse over the Random Icon, (picture below).

https://steamuserimages-a.akamaihd.net/ugc/1773823490340956193/35783140F3F8379D191FE81D9EACCA6A6546DDEC/?imw=256&&ima=fit&impolicy=Letterbox&imcolor=%23000000&letterbox=false


Once its hovered over, it will display on screen. Proceed to "left-click"

You have successfully clicked on the Random icon in Team Fortress 2.