We need to create a webmap to use in our application. If you haven't already set up a developer account for ArcGIS Online, go to https://developers.arcgis.com/en/sign-up/ to sign up for a developer account. Once you've signed in, click on Map in the top menu. It will load an empty map much like the image at the beginning of the chapter.

We can start by saving a copy of our map. This will allow us to name the map, write descriptions, search terms, and so on. In the toolbar toward the top, click on the Save dropdown and select Save. This will create a dialog popup that will let us enter the name of our map, write a summary, and add tags that make it easier to search for our map. We can put the map in our base folder, or make a new one for the application. Add Y2K Census Map to the title, and give a brief description. It should look similar to the following screenshot:

Once you've clicked SAVE MAP, the map should have a new name. If you look in the URL, you'll also notice some...