The correct way to reference the website will depend on what kind of citation you need to use. You can check out https://owl.purdue.edu/owl/research_and_citation/resources.html to figure out how to cite in basically any style.
If you don't have a specified citation style, I would just use MLA. In MLA, that website would be referenced like this:
“The Power of Where.” The ArcGIS Book, learn.arcgis.com/en/arcgis-book/chapter5/.
The trick is to make sure you use the same citation style for every reference in the same assignment.