This little tool allows you to setup the correct internal date and time for your system.
You can set the date on the left and the time on the right:
To change the year, click the little arrows on each side on the year.
To change the month, click the little arrows on each side on the month.
This updates the month view where you can click on the current day to highlight it.
It is recommended to check the time zone settings are correct for your physical location. Click on the Time Zone 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.