Change image in bottom1

Hi,
I'm trying to change the background image in this Quickstar but do not understand where I have to. It 'a link to a picture on the server Gavick.
Can you help me?
Thank you

Hi,
Probably we talk about background images from active tabs
In Module Manager find modules published on : tab1 , tab2, tab3 and tab4

tab1-4.jpg

But the most important is Tab1 - check

thanks!!