Dig out the topsoil where you plan on planting your herb garden.
Lay out bricks in a circle fashion where topsoil has been removed. Other shapes are useful as well, but a circle is usually the most visually appealing for such an herb garden.
Create compartments with separate rows of bricks within your garden circle (think "spokes" within the circle).
Add a second row so that each spoke is at least two bricks tall.
Fill the herb garden sections with compost soil until it is level with the top layer of brick.
Plant your herbs within the compartments of the circle.
Water them well; especially upon first planting, to establish rooting.