You must have Python 3.7 or newer installed in your system. Run the following command to install package orthogram from PyPI:

$ python -m pip install orthogram

Note that Orthogram depends on pycairo, which provides Python bindings to the Cairo graphics library. On Windows systems you should have no trouble with the installation, since PyPI offers a binary package for this OS. On Unix systems, however, you must have the Cairo package installed in your system, including headers, as well as the compiler tools necessary for the build. See the Getting Started guide in the pycairo documentation for further instructions.