How many kids? If you are with 3 or more people, a car service might be cheaper and definitely more convenient. Definitely after an overnight flight.
Otherwise:
The train station is near terminal 2 F and you follow the signs. This site might help to give you an idea where it is. Skip the part about the RER.
https://parisbytrain.com/charles-de-gaulle-airport-cdg-to-paris-by-train/
Give yourself plenty of time with bagage and customs to get to the station, if you are unfamiliar with the station, I think it is best to take a later train and have breakfast at Paul's or Relay, instead of rushing.