[Help] [Request] Shadow behind img in post.

Hello all. My english is sucky, but i’l try somehow……
On this url – https://www.deviantart.com/deviation/16509972/ – all images has own smooth rounded corners shadows. It apears in second place after image is loaded. I think shadow somehow autogenerates on img. My question: It’s posible to implant this (plugin or whatever it is…) in to WordPress? Then doing a post i write standart <img src= etc.
…only image in post looks “”~ugly ;]
Thanks in advance ??
P.S.
If it posible- step by step, because i’m not that good at coding like u r guys 8)