To set up on a local production environment, you need vagrant installed.
Then, just get started:
$ vagrant up
To get Sass running:
$ vagrant ssh -c runsass
That'll keep watching for any changes and update the CSS on the fly.
If, however, you just want to compile the CSS once, simply omit the --watch argument.
Having played around and edited things, you'll want to put the VM to sleep (otherwise the host machine will be slow ...)
$ vagrant suspend
... or, if you are homicidal, you can
$ vagrant destroy
which will completely remove the VM and free up diskspace (if you need it).
Now stop wasting time reading README files and write some code!!!