How to change the Color in GK John

Can anybody tell me how to change the background color in GK- John?

Not the color of the background I mean the color of the parts like "Hello", "CHECK OUT MY HOT WORKS" .....

The 'Hellow' module uses an image as background, if you don't use and want to change the color, you can override this css rule:

#gkHeader {
    background: #333;  /*change to your desired color*/
}

For the 2nd module, you can override this:

.frontpage #gkPageContentWrap {background: #f1f0f0 url('../images/pattern_bg.png') repeat 0 0;}

Regards