First, click on Post Reply and then look for the paper clip icon and click on it. A new smaller window will open - browse for the image you want to upload. If it fails, it's likely because it's too big, so you'll need to re-size. If it uploads, click Close Window (upper right). Go back to the paper clip icon and click on it. Insert the image (you won't actually see the image here, just a drop down box with numbers). Let me know how it goes!