Read the Changelog.
You can download F.O.X. from GitHub.
There are several versions available, depending on you platform and method of installation:
Fox-(version).tar.bz2 : Fox for Linux (source code)
Fox-(version).dmg : Fox, precompiled for MacOS X - a Universal binary (powerpc and x86) is available
Fox-(version).zip : Fox, precompiled for Windows
Then follow the installation instructions.
You can also download the Fox manual on the same page, which is a pdf version of this wiki.