The simplest way to get started with Compojure is to use Leiningen, the standard Clojure build tool. If you haven't already, download and install Leiningen. You'll need Leiningen 2.0.0 or later for these next instructions to work.
Next, create a new project using the "compojure" template:
lein new compojure hello-world
This will create a basic project skeleton containing a minimal web application.
You can now change into the project directory, and start a development server using Leiningen:
lein ring server-headless
The dev server will start up on port 3000. If you make a change to one of the source files, it will automatically reload it for you.