Built a raised bed a few weeks ago following this rough plan: www.sunset.com/garden/perfect-raised-bed-00400000039550/
I did it 3 boards high to keep the dogs out as our small dog loves to eat vegetables. Took about a day and half to build. Still need to finish the drip line you see poking up front but otherwise things are growing well.
Found out if you build a bed out of cedar you need to line it with something to keep the wood from contacting the soil since cedar has plant killing properties in it (why it lasts so long). I bought some plastic liner and just stapled it on the interior. Notes above describe the plants.