Is there a calendar gadget that can be put on the computer desktop?

Right-click the mouse in the blank space and click the gadget at the bottom.

After clicking, a dialog box will appear, which contains many gadgets.

Right-click the small icon of the clock and select Add.

Then you will see a clock gadget on your computer desktop.

You can add a calendar in the same way: right-click the calendar and click Add. The calendar will appear on the computer desktop.