To get started with Flamingo 4 download the binaries and follow the [/wiki/Install installation documentation]. The releases can be found here: http://github.com/flamingo-geocms/flamingo/releases
(Older versions can be found here: http://svn.flamingo-mc.org/trac/wiki/Download|Archive)
If you want to change things in the code or build your own version you can download the code with a GIT client. See https://github.com/flamingo-geocms/flamingo
More info about building from source can be found BuildFromSource page.