Do TSA officers follow you around?

This summer I am taking a plane alone for the first time, from England to America. The airline is US Airways. I am 14, and when I looked on usairways.com it said that "Children 5-14 may travel unaccompanied on nonstop flights for an additional $100 fee each way. US Airways istance is required." What do they mean by 'istance'? If these are security officers, are they going to follow me around everywhere? Will I be allowed to walk around the airport/eat/shop after I go through security? I understand if people are helping me get to the correct gate, but are they going to be with me the whole time? Help please :)