How can I use this timer?
It looks like you pull the red tabs in or out to have the device turn on or off for a given 15 minute interval. I'm guessing the black arrow is pointing to the current time. The switch on the side is to manually turn it on or off (or perhaps permanently off or on the timer). You'll just need to test it to see if the tabs being in or out correspond to on vs off. And to know about the switch on the side, try turning it off and see if the timer moves after 30 minutes.

To adjust the current time, you can turn the dial clockwise, but not counter clockwise.