Starting my own small(ish) herb garden?

I have a 8ft x 10ft stretch of land in my back garden. It's walled, i'd say the walls are maybe shin level and the base and walls are made of concrete. I'm thinking of filling the bottom of it with gravel for drainage, and then filling the rest of it with soil to start my own herb garden. I've never even tried gardening before (until recently, i've never lived anywhere with more than a windowsill plantpot). Does anyone have some general tips for me on what soil to use generally for herbs, how to keep out pests, and anything else i should be aware of? Any help would be greatly appreciated, i feel like i'm already getting the "gardening bug" and i'm only in the planning stage :)