Welcome to Japan Guide ( Narita Airport )
I'd show you the procedures after disembarkation from the plane to how to take the train to Tokyo proper with photos. This is all about the Terminal 1, however the principal structure is very similar to each other.
Then you need to clear customs. The officer may ask you to open your bag.
As you exit the airside, you are in the south wing.
Those who need to catch the train asap, go downstairs by escalator or by lift.
JR Line (Narita Express, etc details), or Keisei Line to Nippori and Ueno
While the JR Narita Express boasts its good connections to major stations in central Tokyo and Yokohama, the Keisei Skyliner and the limited express feature their reasonable prices to Nippori and Ueno.
Those who catch the limousine bus, there are two ticket counters.
This one is open from 6:30 to 23:00, and this from 7:00 to 21:00
Other useful facilities in the south wing.
Signpost toward courier counters and the counters
Showers / Official shower and dayroom info
For other info, refer to Narita Airport official website.
Hope this helps.