No stable versions of OpenTIRE have been released yet. You can however down the code base from the link below. You can also browse the code in the projects repository.
OpenTIRE is a Python module, as such you will need to have a distribution of Python installed. OpenTIRE recommends the Anaconda Scientific Python distribution which also packs many of the scientific libraries available for Python. OpenTIRE however works with any 2.7.x version of Python.
If you are new to Python and are looking to easily get started, JetBrains PyCharm Community Edition software offers a user friendly interface, that is not very different from for example MATLAB. Another option is to use IPython Notebooks that are available within the Anaconda distribution.