First, put this code in between your html/css tags. This is where your main image goes. Only change what is in capital letters.
Next, put this code in your coding. Change what's in capital letters. For instance, the width of your div, height of your div, and left and top positions of your div. If you want your height to be infinite just erase the capital letters and leave it px.
Finally, put this code in and repeat the previous step.