One of the best ways to keep your site organized is to create a separate folder on your floppy in which to store your images. This keeps your filing system nice and organized, but can create some confusion. You will place all your images, whether they are gifs or jpegs, in this folder.
Source means what is the name and place of the image.
You must put the name of the image, plus its three-letter extension, either .gif or .jpg. You must also put the name of the image in quotation marks. However, since you have put your images into a separate folder, you need to tell the browser where to look for the image. Save your work again. Go to the Browser and reload your page.