Wordpress Theme clean up and update

Hi, I need help cleaning up my wordpress theme (which I love - www.setinparis.com) i don't know how to back it up and last update lost my shortcut buttons. Too scared to update the theme but they have cool new updates (ie. background shortcode) I would love to add. Trying to add shopping cart functionality - all good and added UPS plugin, but now buy now button not appearing to finish it:-( Think the back end of the website needs clearing up. Been trying to do all by myself but few problems I can't.

Also, in future would like a mini-IMDB database within the blog, SEO re-do/advise and a mobile app design.