Having passed though passport control before picking up your bag you simply walk out into the hall and so to Paris.  The easiest route is via the Roissybus at a cost of eight euro which takes you to the Opera house in the centre for Paris normally a trip of about 50 minutes depending upon the traffic.
All sounds very easy and it is when you know but a quick tip when arriving at any of the Charles de Gaulle terminals is to remember which one of the three you have come into and which one you are going back out of.  Remember also that terminal 2 is particularly large comprising of 2a through to 2F.  Obviously you will also find this on your ticket but I can assure you that I have seen more than one traveller going back out to the airport on the bus panicking because they did not know which terminal they should get off at and missing the stop.
All is not lost if you do miss your stop and end up at terminal 1 the next stop for the bus is back into Paris but you can get off and catch the train that runs back and forth between the terminals.  This is a bit hard to find, especially if you are panicking over your flight, but the staff at the airport are all really helpful and the level of English is good especially compared to the level of French found at UK airports.
The only last thing to say about the Roissybus into Paris is that on the outskirts of Paris the bus stops in the street and one is tempted to get off since the driver has got off and disappeared.  Do not.  The driver may not say it to you but this is just a changeover wait until you are parked outside a building with lots of gold bits on it this is the Opera house and as far as I can help.