Commands can be typed in your Console. There are 2 ways to open your Console.
1. At the bottom, on the left, you find several icons. When you hover over them there will be a small pop-up explaining what each does. The console icon looks like a piece of paper with text and a blue frame around it.
Click the console icon and within your interface, near the bottom, your console will open. Below it is a command bar where you can type commands.
2. You can also access the console from the Menu by going to View --> Console
If you want to clear the text in your console, there is a button labeled Clear in the top right-hand corner of the console.