live and let live.与民争利的政府必亡
Generally, you should use the free installer, which contains all of the dependencies and will get you up and running with a few clicks. See the Dev Environment Setup if you'd like to deal with dependencies on your own.
See the Dev Environment Setup guide on GitHub, which will walk you through the whole process from installing all the dependencies, to cloning the repository, and finally to submitting a pull request. For slightly more information, seeContributing.