You should use either Firefox or Google Chrome as your web browser; there may be compatibility issues with Internet Explorer or Edge.
To test that Jupyter is working, select "Python 3" under "new" from the top right. You can try typing some code here, then press ctrl+enter to run it (or click on Cell > Run Cells). You should be able to produce something that looks like this:
After you have Jupyter installed, make sure you can download and open the sample notebook from the courser website (under Lessons). You will need to open the notebook by navigating to it from the Jupyter dashboard in your web browser.