Hi again,
you can add an image like this: Add this css code to your css/custom.css

.top-section {
background: #ffffff url("img_tree.png") no-repeat right top;
}

>> Image path must be changed: ../../images/your path/image.jpg

www.w3schools.com/css/css_background.asp
www.joomlaplates.com/template-customizing