I'm sure you will enjoy your first flights (although nothing like it was when I took my first flight many years ago!).
Here is a handy guide to PHL courtesy of the folks over at the US forum:
http://www.flyertalk.com/forum/us-ai...a-airport.html
In general, PHL is a pretty easy airport for transfers (as long as things are running on time) and has some decent shopping and food options.
Enjoy!