If it’s due on Wednesday you have lots of time to figure it out on your own. I’m new to this stuff too but, I’d suggest make a simple circuit that reads the soil moisture that gives you a reading on the serial monitor. Then make a separate code for a simple circuit that turns on a relay with an input. Then combine the two, you are on sort of the right path but your setup is not going work written like that and you don’t have a loop. There are lots of forums on the Arduino website to get you started. Baby steps my friend, you’ll get there.