this is not really the best answer, but will probably work in most cases by typical users.
you can't simply copy/paste a local image from your own device, for example. it would first need to be uploaded somewhere and then made publicly accessible.
but you probably can copy/paste an image from another website -- well, you're not actually copying the image -- you're actually copying the browser code used to display the image. you don't see the code, because the browser hides all that magic from you in the process.