There are many ways to introduce pre-reading skills and it definitely sounds like your son is showing an interest! This is a great time to start the reading process because everything is new and exciting.
My girls showed an interest at two, so we did many activities. Through those activities they started naturally recognizing, letters, sounds and then words.
Some things you can do are:
1. Put up a bulletin board to display significant letters and words:
http://www.teaching-tiny-tots.com/toddler-activities-bulletin-board.html
2. Make your own books using drawn pictures, photos, postcards and write a word, simple sentence or phrase that your child creates. He will likely remember what he "wrote" and you can praise his "reading."
http://www.teaching-tiny-tots.com/toddler-books-ideas.html
3. Lots of drawing with crayons, markers and even painting. Ask what the picture is and label, display on a bulletin board or wherever you put up special pictures.
4. Above all read, read, read! Read repetitive stories like Brown Bear Brown Bear, rhyming stories, anything he shows an interest in. Continue pointing at the words as you read. Do pre-reading activities like looking at the cover and asking what does he think the book is about. Say, "The Title is....."
5. Does he enjoy helping in the kitchen? Cooking is a great way to develop reading skills. Write out the recipe in large letters, post and gather ingredients and follow along step by step.
These are just a few activities you can do to introduce reading in a meaningful and fun way. Good luck!