using( var host = new NancyHost( hostConfiguration, new Uri( "http://localhost:1234" ) ) )
{
    host.Start();
    Console.WriteLine( "Running on http://localhost:1234" );
    Console.ReadLine();
}
Place this code in your project at the point when you wish to start listening for http traffic.
public class FooModule : NancyModule
{
    public FooModule()
    {
    }
}
...
public FooModule()
{
    Get["Bar"] = parameters => {
        return "You have reached the /bar route";
    }
}