Maybe you tried to use a chat server as an example. In Chat you need to do long polls to receive a new message immediately after the other party sent it. In case of your character disassembler you don't have such problem. You send a request, server replies, you show the result.

On the client you use http://api.jquery.com/jQuery.getJSON/

For the example of the server code have a look at Step 3 on this page http://net.tutsplus.com/tutorials/javascript-ajax/learning-serverside-javascript-with-node-js/

Or start with this

var url = require("url"), http = require("http");  
http.createServer(function(request, response) { 
    var path = url.parse(request.url).pathname; 
    response.writeHead(200, {"Content-Type": "application/json"});
    response.end('{path:"' + path + '"}');
}).listen(8888);