node.js require method can't find javascript file: Module not found

I am very new to node.js and i am follwing a few different tutorials. My goal is to use node with ejs or underscore. My first attempt with using underscore isn't going really well.

I am using bower to manage script dependencies for my project and i was able to pull down the the amd version of underscore under the path public/javascripts/vendor. I am confident that if i were to install underscore using npm, the module would be found and the error would go away.

I thought setting the app.config with this line

    app.use(express.static(path.join(__dirname, 'public')));

essentially uses all static files under that directory? How come then, underscore can't be found..

This i how i am using it by the way.

   var _ = require('underscore-amd');
app.register('.html', {
    compile: function(str, options){
        var compiled = require('underscore-amd').template(str);
        return function(locals) {
            return compiled(locals);
        };
    }
});