How to add drag and drop interactivity to a website

I want to build a website for a balloon store. On this website, I'd like for customers to be able to drag and drop pictures of balloons into a window and arrange the pictures however they want; this feature will help customers better visualize what balloons they want, and how they can arrange each balloon, balloon bouquet, etc. I've looked and looked for tutorials on how to do this, but haven't found anything for exactly what I want to make. Any help, tutorials, etc., are greatly appreciated.