Some links about gardening.
This Old House: How to build a raised vegetable garden These are very detailed and professional steps. I have seen other variations where you don't need to till the soil underneath (it can even go on a patio). One suggestion I read elsewhere was to put chicken wire at the bottom to prevent moles from burrowing up into your garden. Another suggestion was to put bricks around the outer edge if it's on grass to make a mowing boundary.
Vegetable ideas: cucumbers, summer squash, green beans/string beans, herbs such as lavender