Check out Mother Earth News
They give some really easy ways to start an instant garden for the novice. Garden in a bag and hay bale gardening are among my favorites. (I just posted a question on answers to see how others are doing with their hay bale gardens… I’ve been doing this for 3 years and love it. Anyway, as the answers start coming in you might want to see what other people think who’ve done it.)
You can also do the old fashioned tried and true method of tilling up some soil, adding some amendments (compost, manure, etc. which are easy to buy at Walmart, Kmart, local garden stores, etc.)
However, at this stage of the game (assuming you live in the USA) you’re probably going to have to buy nursery plants once you’ve got your garden site prepared. But at this time of the year the prices are going down too. Just make sure you buy good healthy plants that aren’t too leggy.
For your first time you really don’t need that much: a hose with a sprinkler attachment is nice, a hoe, a shovel, a little hand trowel, garden gloves, twine, some stakes and you should be off and running. Fertilizer is a good idea, since you want to go organic make sure you buy one that is.
I love gardening! Good Luck!