Wash out a plastic cottage cheese container, and allow it to dry completely.
Fill the container two-thirds full with potting soil. Nutrient-rich potting soil formulated specifically for tomato plants is available at a garden supply store, or a basic, universal potting soil available at most supermarkets is acceptable.
Wet the soil with 2 tbsp. of water.
Poke a finger three to four times into the moist soil, inserting a finger about 1/2-inch deep each time.
Place two to three tomato seeds into each hole, and cover the holes with the surrounding potting soil. This will position the seeds far enough into the soil to receive nutrients and close enough to the top of the soil to grow properly.
Wet the soil with 1/4 cup of water, and place the container in a sunny, warm location. After a couple weeks, the seeds will sprout into a tomato seedling.