You can set the date on the left and the time on the right:
to change the year, click on the little arrows on each side of the year;
this updates the month view where you can click on the current day in order to highlight it;
it is recommended to check that the time-zone settings are correct for your physical location. Click on the button and select the correct place in the tree view;
to change the time, you can then either move the hour, minute and second hands of the analog clock, or change the numbers below.
When you are finished, click
to apply your settings or to close the tool, which will consequently discard your changes. If you want to come back to the current settings, click on .