AutoWater | Automated watering system for potted plants

To begin with turn the breadboard so that j1 is in the top left corner. Next, take a red wire and connect it to the Vin pin on the Arduino. Plug this in to the positive rail on the top right of the breadboard. This will take the direct voltage from the 9v power supply and pass it to the solenoid valve, without first sending it to the board's regulator. If you tried to use a lower voltage, the solenoid valve would not be able to turn. With another red wire connect the positive rail to the near end of a column, on the left side of the breadboard. Immediately below plug in another red wire; take an alligator clamp and attach it to this wire. Connect the other end of this alligator clamp to the positive side of the solenoid valve.
Take the diode and put the side with the white line immediately beneath the last wire plugged in to the breadboard. Plug the other end into row c of the same column. In row b plug in a black wire. Take the second alligator clamp and attach it first to this black wire, then to the negative side of the solenoid valve.
Take the TIP-120 transistor and find the front. With the transistor facing you, plug all three pins into three columns in row j beginning several columns to the right of the diode column. Take a black wire and plug it first into row a of the diode column, then into row i of the column containing the transistor's middle pin. Take the resistor and plug it into the column of the left pin, leaving at least one open pin; in row a of the same column, plug in a yellow wire. Plug the other end of the yellow wire into digital pin 7 on the Arduino.
In the column of the right pin of the transistor, add a black wire. Run this wire into the ground rail at the top of the breadboard. Take another black wire and run it from one of two GND pins on the Arduino to the ground rail on the breadboard. The circuit is now complete!.