Ahhh, case resolved. On my local machine, I had the image in cache it seems, so I uploaded the image via the WordPress interface and now the site finds the image just fine.
As a matter of fact I created the site locally and then uploaded the theme and the database to my server. So localhost:8888 is my local installation. But how come I can see the image on the website?
Actually I would like my WordPress look like this (with some modification):
http://www.fx81.com/
