My Binder setup takes a repo that you have defined on your github page. Copy/paste the url of the repo into mybinder.org to generate the binder badge (see above).
If you open the binder it will automatically generate a run environment that has a terminal and a Python2/3 environment.
If you have an ipynb that is named 'index.ipynb' it will initalize with that notebook.
Dockerfile will define the build environment -- including the install of the programs through apt-get or the like.
requirements.txt lists the python packages that you want to install through pip.