Then gradually add more words. Simple words and every day words, especially those that the child can see on a daily basis. Toy, car, train, book, cup, milk all of these. Pretty soon it becomes a game. First the child will ask you how to spell it, and then they will try.
Repetition is the greatest key to learning.
Learning numbers seems easier than letters. This can be introduced to a child at a very early age much the same as with the alphabet. Sing the numbers in order in a little tune. It doesn t have to be a complicated song, just the numbers. The sound of the voice draws the attention.