add image to background of shopify store and a image to the footer

looking for a shopify extra to add a image to the background of our shopify site on all pages so the image os ni the middle left side of the screen and a image in the lower right corner of the footer on all page not sure if its possible shopify says it is ill attach the middle image that should go on the middle left side of the website under the main banner our website is mechanicpimp.com