Meteor runs on port 3000, unless you specify a PORT environment variable. Try navigating to http://YOU_IP:3000/ and you should see your Meteor app.
You have 2 options. Either you add this to your mup.json
"env": {
"PORT":80,
......
or you use Nginx / Apache as a reverse proxy. If you just want to toy around I would suggest going with the first option since it only takes a second. If / When you want to push your app to production you should look into setting up Nginx.