Step 1: You will need:
A young leafy plant, such a Tomato, Green Bean, Cucumber or your favorite Herb. I used Italian Parsley for this project.
A Two Liter Green Soda Bottle
A Hole Punch
A Roll of Duct Tape
Scissors and/or a sharp Knife
Enough soil to fill your bottle at least 3/4 full
A little Garden Mulch or Bark
Something sturdy to hang your planter with, such as twine, leather string, a cut coat hanger, etc.
A weather resistant hook to hang your planter on
Note: I had stated before that using a green bottle aids in photsynthesis, I stand corrected as you will find explained in the comments below by Dwygrshpr.