It should have drain holes in it, otherwise it will have to be watered very carefully so as not to get the bulbs too wet. Begonia bulbs have a very fine root system and if they stay overly wet for a long period of time, they will surely rot. Simply plant the bulbs just below the surface of an acid type soil, preferably a pasteurized peat mixture. Barely cover the bulbs with the same mixture and water well but not to a point that you have water standing on top of the soil mixture. Place in an area that has good light and watch them grow.
Tuberous begonia start very slowly.
That is why you will want to start them now so they will be ready to plant out of doors when the weather is nice. Everyone still asks me about starting tomato plants now. It s still too early. If you do this now, you will have tomato trees by the time you need to set them out. Besides that, they will probably be spindly and weak as well.