= Mac OS X =
Just download the *.app file and put it into Applications folder

 = Windows =
Download the *.zip file and extract it. The folder contains an executable *.exe file.

 = Linux/ UNIX =
For these platforms, Arboreal has to be compiled from source. Either get the respective tarball or check out the source code. Additional to Java compiler, you will need JFlex which you can get from the [http://www.jflex.de/ JFlex homepage] or as a package in your Linux distribution.