You either have a patch of 'dirt' that can easily be turned into a vegetable garden, or you've ripped up a piece of the lawn. If you've done the second, make sure it's in a sunny location.
Still on the topic of tomatoes, if you have a garden space, consider planting a cherry variety, a slicing variety and paste variety. My favourites are Sun Sugar, an orange cherry that is early and very sweet, Celebrity and Lemon Boy, red and yellow slicing types, and Viva Italias for the paste variety. I prefer the Viva Italias to Romas or Mama Mias because they produce even more uniform fruit. They are good for fresh or canned salsa, good for slicing and good for freezing whole, so you can enjoy them over the winter.
Enough about varieties. How do you start?
Ensure it has been well worked and is reasonably free of grass roots. If it is heavysoil, add compost and/or peat moss. If it is light or sandy soil, add compost if possible, some top soil and manure.
I mud in my tomato plants. This means I dig a hole slightly larger than the pot the plant is in, add water and allow it to soak in almost entirely. Then I pop the plant out of the pot and into the hole. Fill the hole with soil and firm it down around the plant to remove as many air pockets as possible.
Place a large can, wooden shingles, or if you can find them and afford, them use a Kozy Coat or Wall of Water.
Kozy Coats and Wall of Water: These are large plastic circles that consist of individual tubes. When filled with water, they hold themselves up in a t-pee shape. The water warms from the sun, and the whole affect is that of a miniature green house. The tomato will eventually grow too large for this space, so open up the top of the Kozy Coat and turn it down.
Fertilizer: I use a blossom booster variety, 15-30-15 once the plant begins to bloom to encourage even more blooms. Whatever brand of fertilizer you purchase, a no-name or Miracle Grow, follow the instrucitons.
Tomato cages and stakes: These are useful if not absolutely necessary. Some plants, like the cherry types, tend to grow and grow, so they need both cages and stakes.
Water when needed and from the bottom of the plants as often as possible. If tomato leaves get wet too often from above they are prone to tomato blight, a disease that kills the leaves. No leaves, no breathing and no plant. As for watering from above, well, we can't stop the rain, but do limit your own watering from above as much as possible.
At any rate, have fun, get dirty, get green fingers from the tomato plants and enjoy the fruits of your labour, literally!
Best of luck,