If you want to be published by a traditional publishing house, search the internet for reputable literary agents who deal with children's books. Carefully follow their submission guidelines. You may have to send out query letters to hundreds of agents before finding one who will represent you. If you don't take rejection well or you just don't want to wait, you can self-publish, but I'll warn you now that takes a lot more work to sell books than most people think. If you decide to self-publish, CreateSpace is an excellent service.