Go through the images with your child, one at a time and say “This is a____. What is this?”
Your child will answer and you will say, ” Yes, it is a window” or if they don’t know or answer incorrectly you say, ” it is a window.”
Then ask, ” what is the first/beginning sound of window? ” If your child does not know the answer, help them. You can emphasize the sound so your child can hear it. If your child gets it right, ask them to write the letter on a piece of paper or write the letter for them if it is too difficult for your child.