Once you have transplanted your seedling into a nice large container, one with good drainage and preferably lined with a thin layer of gravel on the bottom, you have already done the hardest part of the work involved in setting up your own container garden. However, you will still need to take care of the garden if you want to eventually eat its produce.
Your garden will need two basic ingredients: sunlight and water. Most vegetables grow better in full sunlight. However, some crops, such as lettuce, cabbage, greens, spinach, and parsley, will cope with more shade. Root vegetables, such as carrots and potatoes, can also stand more shade. If you have planted a crop that needs more light, though, one option you have is to move your containers at different times of the day (if you are home).
You will have to monitor your plants to see how much water they need. If you can afford to buy fertilizer for your garden, you can add fertilizer to the water (following the instructions on the label). Alternatively, you can use scraps from your kitchen to create your own compost for the garden — but composting is another topic for another day. When you water your plants, take care not to get the leaves wet, because wet plants are more susceptible to disease. (It’s not a big deal if they get a little wet sometimes — plants in nature get rained on, after all.) It’s hard to predict how often your plants will need water, but you can expect them to need more water — maybe even as much as one watering per day — if they are in a very sunny, hot area. If the weather has been wet and humid, your plants may need less water. Be careful not to overwater, and check to make sure that excess water is draining properly from your containers. If the water does not drain well, the soil may become water-logged, and then the plants can die from lack of oxygen.
How long will it take before you can enjoy the fruit (or rather the vegetables) of your labors? It varies by plant. Lettuce, for example, can be harvested between 45 and 60 days after it is planted as a seed. Peppers, onions, and tomatoes take longer.
Good luck, and happy gardening!