Question regarding to image position

You can also try the helpful information at Using Images.

But to add a shadow to an image is a CSS trick and different from these tricks.

There are many ways of doing this, using CSS filters (don’t always work across all browsers), through the use of borders, or by using a second image put behind the first. It can get complicated.

Since the information you need is widely available on the Internet, and not directly related to WordPress, I recommend you search for “CSS, shadow, image” to find tons of tips that will help you put shadows behind your images.