Linda, My advice, please be swift to hear, is to start experimentally with a 5' X 10' single raised bed made of untreated lumber, second hand even. Make this one bed a little smaller than 5x10 in case you want to enclose it next year, see below. Three ten foot 2X6 is a good start. You might not like this approach to gardening and at least you won't have committed too much to it. Besides, it'll take a bit of scraping and shaping to scrape out a 5x10 rectangle and chuck all the soil into the center. Fill up the frame to overflowing with good soil, compost, manure, grass clippings, anything clean and vegetarian. This is your best chance to amend the garden bed top to bottom so read and think about lime (Byron's recent note is a good indicator for liming.), and other long acting soil amendments. Rather than the "square-foot" gardening technique, though raised beds lend themselves to it, I recommend Ruth Stout's "No Work" approach in which you prepare the beds just once then cover with salt marsh or regular hay, right up to the plants knees as they grow. See a weed? Throw hay on it. Whew! If, as the season wears on, you decide that this is the way for you to garden, then buy your pressure treated boards at the 2x8 or 2x10 dimensions and weather them all the rest of this summer, over winter and use them next spring to enclose this year's work and yes, please, line the new bed's sides with thick plastic. Oh, and if this is a salad garden, you'll want to get going and to make choices that will help produce a "mucky" nitrogenous soil. Unlike your pepper crop, for salads you are just growing leaves. A few boxes of leafy waste from your local supermarket would be great on the bottom of your new bed. The one in the yard, I meant.