If your begonia plant is still living by the beginning of fall, dig up the plants, or cut them, and bring them indoors and they should last inside until the winter.
Tuberous begonias grow from the middle of summer until the beginnings of fall. They can grow from 8 to 18 inches tall. They are slightly bigger then wax begonias.
While the wax species can be in some sun, this kind cannot. Only plant them in areas with a lot of shade.
To grow the tuberous plants, you must plant bulbs. They do not grow from seeds. You can begin planting them in the winter. You must start them indoors though. Find a well-drained potting soil, and plant the bulbs in the soil, in a pot.
Be careful not to cover the tuber with too much soil. They only need to be barely covered. Water it enough just to keep the soil moist.
Once the weather begins to warm up, and the frost is gone you may then transfer the begonia plant outdoors. To keep your plant growing and healthy all season, fertilize it every so often. About once a month should be fine.
When the fall comes, you can dig up the begonia bulbs and store them inside, until you are ready to start the whole process over.