I have lived in Paris for about 20 years, may be i can help you.
In the CDG airport, you will find a train station where the TGV can take you outside of Paris and also straight to Disneyland Paris), and the RER (regional train) that can get you into Paris.
Visit this website for the Paris Public Transport:
http://www.ratp.fr/en/ratp/c_5000/accueil/
or
www.sncf.fr for the french railways and TGV
Have a safe trip