installation on mac osx:

/usr/local/bin/gem install mdpress

path is non-std for me:

alias mdpress=/usr/local/Cellar/ruby/2.1.0/bin/mdpress

create the project, simply:

$ vim foo.md

now run compiler in watch mode:

$ mdpress -a foo.md

....this creates a dir called foo with js / css / etc.

check it in browser:

file:///Users/gleeco/path/to/foo/index.html

PRO tip: run chrome w/ developer panel open and cache disabled as you edit