Images over website border – how to

Hello,
here i am with a new question :)

I’m trying to recreate an effect from an old website (http://www.cantinabotti.com/ita/index_ita.html) on the new one.
I would like to put images across the border of the website.
I’ve been able to manage a new css class for the image to move it to the left but it is hidden by the border. I tried also to change the z-index without success.
Here you can see what’s happening http://www.cantinabotti.com/sito/
Any hint on how to put the image over and across the border?

THank you!

Alex