0bin comes with a complete theming support, but for now it’s not well integrated.
If you wish to create your own theme, you’ll need to create templates similar to the ones in zerobin/view, and add the path to the directory containing them to the configuration file.
You’ll also need to copy static files from zerobin/static to a new directory where you can edit them. And you need to add this directory in the configuration file too.
Of course, if you look for something simple, you can just edit all files in place/
If you have serious theming needs, please contact us so we improve the support.