Getting Started Instructions give error: "No :main namespace specified in project.clj."

[snowch]

When I follow these steps (as per the getting started section of the website):

lein new noir my-website
cd my-website
lein run

I get the following error:

No :main namespace specified in project.clj.

Please let me know if more information is required for debugging purposes...

[aoeu256]

Me too I get this error, I am on Windows.