To begin with, get your hands on a used timber pallet. An easy way to do this is just Google ‘used pallets for sale your city’, there will be a number of options for you. You will also need landscaping fabric, a staple gun, good quality potting mix and all the herbs you love to cook with.
Check out Design Sponge for easy-to-follow steps with very useful pictures.
This is a great weekend DIY project and you can get really creative with what plants you use (consider the placement of the wall and how much sun / shade it gets). Consider painting the pallet in a bright colour before building for a fresh ‘pop’ of colour, or for a larger space use a number of pallet gardens for a dramatic look.