Hi Susan,
I'm assuming you've seen the
Charles de Gaulle to Paris by RER Train article so I'll assume you can make it to
Gare du Nord station. If not, let me know.
From Gare du Nord, you need to take an RER E train to Haussmann St-Lazare station (see this photo of the
RER train sign at Gare du Nord).
Haussmann St-Lazare will be the terminus station for the RER E train. From there you need to switch to Metro Line 3 in direction Pont de Levallois Bécon. That will take you to station Pereire, which is... wow,
right beside your hotel.
Nice choice!
Ben