1. From the apps menu, select Trailhead Data Manager.
2. Click the Download Trailhead Dataflow circle.
3. From the app menu, select My_First_Analytics_App.
4. Click the Download Dataflow for My_First_Analytics_App for Trailhead button, and save the file to the desktop. It should be called My_First_Analytics_App_for_Trailhead.Json.
5. Go back to Analytics by selecting it from the menu at the upper right.
6. Click the gear icon, and select Data Manager. From the menu in the upper left, select Dataflow View.
7. Scroll to My First Analytics App. Open the menu on the far right opposite the app name and select Upload.
8. Click Select a file, navigate to the file you just saved to the desktop (My_ First_ Analytics_ App_for_Trailhead.Json), and select it.
9. Click Open, and click the Upload button, and then click the Done button.
10. Finally, open the menu on the far right next to the app name again, and select Start.
11. Click the Refresh icon to refresh the dataflow list. You might have to wait a minute or two and try again until you see a checked green box next to My First Analytics App.

From : https://trailhead.salesforce.com/en/modules/wave_apps_basics/units/wave_apps_creating_wave_apps

I tried doing all steps .. but in step 11, it wasn't a checked green box .. it said failed instead.