Add a note to make it easier to get up and running

README.md

@@ -3,15 +3,24 @@ Scratch Extension Site
 
 
 ## CSS
-The project uses [Bourbon][], [Neat][], and [Bitters][] for CSS. Don't edit
-`css/scratchx.css`, instead edit the files in `sass` and develop with:
+The project uses [SASS][] with [Bourbon][], [Neat][], and [Bitters][] for CSS.
+To install `sass`,
+
+    gem install sass
+
+Don't edit `css/scratchx.css`, instead edit the files in `sass` and develop with:
 
     sass --watch sass:css
 
 For a quick webserver at http://localhost:8000, run from this directory:
 
     python -m SimpleHTTPServer
 
+If 8000 is in use, change the port number to e.g., 8001 with
+
+	python -m SimpleHTTPServer 8001
+
+[SASS]: http://sass-lang.com/
 [Bourbon]: http://bourbon.io/
 [Neat]: http://neat.bourbon.io/
 [Bitters]: http://bitters.bourbon.io/