The argument to Import should be a path to where the image exists on your computer. You probably don't have that image on your computer. If it is on your computer, then it's not in the same directory as the notebook where you're running this code. If you type Import[", you should see a little popup that says "File Browser". You can click that to search for the file you want to import.

If the exact image isn't important to the tutorial, you can use one of the built in sample images.

ExampleData["TestImage"]

This will give you an output that looks like this:

{{"TestImage", "Aerial"}, {"TestImage", "Aerial2"}, <<...etc...>>, {"TestImage", "Volubilis"}}

You can choose one of those:

ExampleData[{"TestImage", "Apples"}]

If the tutorial is about Import per se, then you'll need to have a file on your local computer that you want to import.