Migrants to IJ, 2007

OK, there I was, happy and thrilled with my ij layout and decided to change the mood icons. That's ALL I did and I immediately lost my layout. I managed to get it back to the three columns and changed the colours again, but even though I enter the header url and the size and do everything as before the damn picture will NOT show up. SO SORRY to be a complete pain, but...any advice? What did I do/am I doing wrong? Any ideas? Or should I start again...