If you want to try to grow some of your own food and don't have the space to plant a garden, then growing lettuce in a garden container is a great idea. Lettuce is one of the easiest things to grow in a flowerpot and it likes the cooler weather.
To get started select the containers you will use. Terracotta clay is great because it breathes and it healthy for any root system. Make sure it's got some depth to it. 6" of depth and a drain hole is a great place to start. We also like a generous sized flowerpot so that you can get a variety planted. Head to your local garden center and buy the types of lettuce that interest you the most. Get a six pack of starter plants, and a small bag of potting soil.
When ready to plant make sure the pots are clean. If not use soapy water and let dry. Cover the drain hole with pot shards so that the soil doesn't wash out. Fill with soil and then push the plants into the spaces you want. Make sure they are about 4" inches apart. Tamp soil down about the starters and give them a good drink of water.
When placing the pots, make sure they are in a location where they will get at least 6 hours of sunshine a day. Keep the soil moist and fertilize occasionally.
Your lettuce should grow during fall and some winter.