As you will see on the map I posted earlier Narita Express arrives on the Sobu Line platform on Basement Level 5 (B5) at the bottom of the map. Go up the elevators or escalators but DO NOT go through ticket gates when you reach the main concourse (still on a basement level). Once you go "landside" on the Marunouchi side of the station it will not be easy to go to the Yaesu side which is at the top of the map. Keep following the Yaesu (八重洲) exit signs. Do not go through the Shinkansen ticket gates as I once did (and I understand the language!). The Yaesu Central ticket gates are probably easier to find than the Yaesu South ticket gates which are somewhat hidden near the Shinkansen gates.

Google Maps and Google Street View should give you a good idea of the area around the hotel.

This is looking back towards Tokyo Station from outside the hotel.