[TYPO3-english] Change top image (orange) background in introduction package

[Francesc Juliana]

Hello everybody:

I am adapting introduction package for a new site.
I would like to change the background image on the top. I have been 
searching through it's templates , css stylesheets and TypoScript. I am not 
able to discover how introduction package manage to place it on the page.
In source code of frontpage doesn't appears the img html tag.

Anyone knows how to do it?

Thanks in advance.

Francesc