The first screen you see when you sign up is the "My day" view, which is also the default view or your "home base".
Basically you are looking at "today". You can see the date on the top left in the sidebar.
Marvin takes a day to day approach to getting things done. So each day gets its own view.
This has many benefits, like giving you a sense that each day is a fresh start and helping you to focus on the next steps instead of feeling overwhelmed by the workload for the next weeks or months.
Depending on what strategies you have turned on/what workflow you use, you use the day view to work off your daily to-do list, make intentions what to work on that day or use it to pick tasks to work off.
Whatever you get done that day, will go to the "Completed" section for that day.
Navigating to other days
You can go to any past or future day by using the forward and backward arrows on your keyboard or the "previous" and "next" buttons in the left sidebar.
You can also click the little calendar icon to pick a specific day from a calendar:
Returning to today
To go back to "today" either use the cmd+down keyboard shortcut or click on "My day":