hello i follow this tutorial but it works for me 
http://www.avacweb.com/t1000-how-to-modify-the-post-background-of-a-specific-user

but my problem i dont want it color i want to add the image like this.



its possible to add that photo in this code.

Code:

.specialposts {
  background: none repeat scroll 0 0 #333333 !important;
}

instead of using this color "#333333" i want to use this picture


forum version: Phpbb2
Forum: my forum

Code:

.specialposts {
  background-image: url('http://imageshack.us/a/img402/3778/14k8i0w.png') !important; background-repeat:repeat-y;
}

maybe try this one?

when i use that code it will cover all the post like in FM ?

well if you follow the steps in the tutorial you provided the link to and you do it correctly it should only change the posts of the users that you want :)

i know but it is cover all post of the user ? like in FM

i try the code and it result this :
https://i.imgur.com/jg70DHK.png

the gradient picture did not cover all the post

try to add

Code:

float:right;

to the code and tell me if that solves it