In MINIX there are three window managers available: Tom's Window Manager, Joe's Window Manager and Equinox Desktop Environment.
The first one, twm, is installed by default with the X.org package and the second and the third can be installed through the pkgin (tool to manage pkgsrc binary packages) utility.
To start EDE you need to edit your ~/.xinitrc file and add a startede line (usually at the end). Afterwards, typing startx on the command line will start EDE.