Hello,

Thank you very much for choosing our theme and for contacting our support.

1. Enter the FAQ page and change the background image in the page settings https://xtemos.com/docs/woodmart/options-for-pages/

2. You can set the sizes of images in the Theme Settings > Product Image > Images http://prntscr.com/ldf46r Also set the image sized in Appearance > Customize > Woocommerce > Product Image

Best Regards