Get some magnetic letters and teach your baby a letter each week. You can start at the beginning and choose the letter a. Introduce the letters as capital and lowercase, so your child knows the difference. Then spend a moment each day creating words that start with the letter a. When you begin this, you should start with words that have the short a sound. You can show your baby words like ant, apple, ax, etc… Once you have shown your baby the letter a and words, move on to a new letter. Your baby will naturally learn phonics in this manner, without formal lessons.