With the help of your mouse, click on the first field (Date field), or just set focus on the first field. It will automatically show a calendar displaying the current month with the current date selected.
You can select a date from the Datepicker using your mouse. Once, you select the date, the focus will shift on the next input field.
If you don’t want to use the mouse to select the data, then hold the control key (Ctrl) on the keyboard and navigate through the dates using the left or right key. Press Enter key to select the date and switch focus on another input box.