Change font in header and over image

Hi. I have installed google fonts add-on, so have been able to change the font for the page. But where do i change it for the hater and over the image. Is it a paragraph, heading 1-6 or other? Question 2: In the webshop it shows image and text for categories. Is it within the theme this images must be made bigger or is it within oscommerce settings? You can have a look at the page for better understanding. www.julegaver.as