How do I get my 3years old on preschool?

If I am reading the question right you are asking how to get your 3 year old enrolled in preschool. Well fist you need to find a preschool that takes kids that young normally there is a waiting list so you need to start looking now. Not very many preschools take kids that young. Now if you are asking how to get your son ready for preschool well he only needs to be potty trained they will do the rest also dome preschools will help you with potty training if you can get him in. Just tell them that you are working with him and they will need to help him also.