Using the Home page
The Home page gives you an overview of your data sources and critical incoming events. You'll be on the Home page by default when you log in, but you can also get to the Home page from the buttons on the left.
Chart and list view
To switch between chart and list view, click the list button.
Getting more details
You can see here that Discover is automatically filtering for events from the selected dataset (from the chart on the Home page),