I believe you will need a wireless network for the Remote app to work. If you visit this page you can figure out how to set up a wireless network between your iPhone and your MacBook.
Once you've done that, just open Remote App and iTunes. Your iPhone will show up in the iTunes sidebar (wirelessly). Your iPhone's screen will show a 4 digit passcode. You'll take that passcode and click on the iPhone that appeared in the sidebar in iTunes. There will be a place to enter the 4 digit code on that page. Enter it and your done. You can then control iTunes from your iPhone.