H.J.
I like containers. Get a "garden soil" mix from walmart, home depot...anyplace like that. It generally has the fertilizer in it already, good for 3 months, which is about all you need for veggies. If you do one plant per pot, use a pot about 10-12 inches across at minimum, and at least 18 inches deep. You will need a very large pot or trough type pot for the spreading type plants (cucumber is a ground vine, and so is squash). MAKE SURE you keep your jalepeno AWAY from your green pepper, or your green peppers may become hot (this happened to us one year).
If you decide to just put then in the ground, pick a sunny spot, clear the grass/weeds away, and rent or borrow a rototiller. Also make sure the spot you pick doesn't tend to flood or hold water when it rains. You want good drainage. If you like, you can work a time release fertilizer (osmocote is a good one) into the soil as you till. I've had good luck gardening in the past without fertilizer, location is more important.
Make sure you leave ample room for your plants to grow and spread. Get a cage for your tomato plant/s. One cage per plant. You should be able to read the label to get the grown size of the plant and spacing information for planting. Lots of gardening websites out there, too. Or a basic gardening book from the library.
Have fun, and don't forget to weed and water!