I would say he is too young for that. In order for a child to be able to spell they have to have the hand eye coordination to hold a pencil correctly which a two year old doesn't have.
I run a preschool program and teach two year olds these things:
Colors
Shapes
Counting
Letters
Coordination via action songs, coloring, playdough etc.
I use blocks or refrigerator magnets to teach letters and numbers along with
songs. I use a phonics song....A says A, A says A, Apple, Apple, A, A, A.
For colors and shapes I cut out shapes of the same color, usually eight of them. I tape one shape on the outside of a paper bag and get the children to drop the a shape into the right bag. I get them to say each color and shape as they drop it in. After that is mastered I use multiple colors for each shape so it is different each time.
Colors and most things are started from birth though. Even when I am changing a diaper or clothes I tell them I am putting their blue pants on their left leg for example.
They can count everything they do, and sing counting songs. Put a number on the floor and have them put the right amount of objects next to it. Paper bags work well too.
Here are some places to get ideas. There are some wonderful things you can do with them to nurture everything they need to know. I use Enchanted Learning for an older age group mostly, but I do get ideas or simple activities from there as well sometimes.
I don't use anything that speaks to them. I was taught that when a child hears a monotone robot voice that can inhibit their speech. I would also look at A+ Child Development. It is also called Stepping Stones to Success. It is a fantastic program for ages birth to twelve. I have it for my son and it is an amazing program that will aid in teaching children at their own speed.
Curriculum and resource suggestions for children from birth to age 8. -
http://www.letteroftheweek.com/index.htm
Free lessons and activities for Toddlers, Pre-Schoolers, and
School-Age children.
http://www.atozkidsstuff.com/toddlers.ht
5000+ free printable pages and worksheets
abcteach -- 5000+ free printable pages and worksheets
Preschool and Kindergarten Activities
Enchanted Learning's On-Line Help
Early childhood activities and lessons
http://www.kinderart.com/littles/litles.
First-School Preschool Activities and Crafts
First-School Preschool Activities and Crafts
Preschool Education
Preschool Education: Discover The Fun In Learning
Preschool Activities & Ideas for Teachers, Parents and Grandparents
Preschool Express by Jean Warren: preschool activities, games, songs, crafts, art, music, learning, skills, stories and patterns