If your board has no printed labels, check out its pinout diagram documentation (found on the board's Arduino Store page). PWM pins in the diagram have the same tilde sign in front of the pin numbers.

This is a wiring diagram that [Soranne] put together when developing a method of programming PIC microcontrollers using an Arduino board. You can see that he takes care of the 12V issue by connecti… ...

I connected one soil probe to power, and the other to ground through a 10kΩ resistor and to Arduino's analog pin A0. I did the same with the thermistor and photoresistor, but connected those to ...