"sudo apt-get install xmonad xmobar xmonad-contrib dmenu"
You don't technically need xmobar or dmenu to use xmonad, but this is
probably the easiest setup to make.
You'll need to make simple ~/.xmonad/xmonad.hs and ~/.xmobarrc config files.
(If you don't fancy the idea of making config files.
I won't describe the process here, but I'll link you to mine, if you'd like
some reference. There are also a lot of great tutorials for configuring
xmonad.
https://wiki.haskell.org/Xmonad/Config_archive/John_Goerzen%27s_Configuration
http://jadedmeta.net/mirrors/Cool%20Stuffs/xmonad_config/
Those links should help you get started.
After writing the xmonad and xmobarrc config files, you'll be able to select
xmonad from the login screen. (A little circular icon next to your username
allows you to choose your DM or WM)
