howto use css to display a featured image on one page, other pages random

Hello!
I tried to get my firm blog page (http://electronics-pcb.com/blog) to stand out from other pages by setting a featured image to it (twenty-eleven).
The idea was to get this particular page header image to display Blog, but the random header image seems to prevent this.

I noticed one related answer on this site by alchymyth, but the problem is that his advice tells how to use css not to display any image 🙂
Can anybody help me with this css problem, I do not want install any plugins to do this…

Here is Mr. alchymyth’s original css solution not-to-show header image:
> if you know the page id of the pages where you would like to hide
> the header image,
> then add something like this to style.css of your theme:
> .page-id-13 #branding img {display:none}
> replace 13 with the page id of your page; and repeat the line as
> often as you need, with
> different page ids.

help would be greatly appreaciated. Especially since I already made the image I would like to show 🙂

esa