You can create an image attractive by using shadow or border-radius, code's are given below use this code in your post or article were you want to show image.
Shadow Code:- box-shadow: rgba(0, 0, 0, 0.8) 0px 0px 8px;
border radius Code:- border-radius: 10px;<img src="image link" style="border-radius: 10px; box-shadow: rgba(0, 0, 0, 0.8) 0px 0px 8px;"/ >
Normal image
After adding shadow
After adding shadow and border
Also You can use this in blogger theme - Edit Html section for easy access, first remove <style>and </style> tag and paste CSS Code above "]]></b:skin>"
then paste Html code in your post, and add download link, show you can easily use shadow box by just applying Html code in post.