I’m so confused. I’ve been trying to figure out transportation from CDG Air France terminal 2 to Gare de Lyon near my hotel. I’d like to take train vs FREENOW due to cost but I can’t figure out how to get started. I think I need to be on RER B to start but how? Then I switch to RER A at Les Halles? Do I buy 2 tickets? For this novice it seems confusing. I’ve never really done public transport. Any idea the cost? Any help is appreciated greatly.
You just need one ticket to Paris, which you buy at the RER station (there are machines, the line is long, there is no way around it). Price is about 12€.
The RER B station at Terminal 2 is well-signed, just follow signs to "RER" or "Paris by train". The station is the end of the line, all trains go to Paris. You need to get off at Châtelet-Les-Halles and cross the platform (no stairs) to get the A train eastbound (destination can be Boissy Saint Léger, Torcy or Marne La Vallée), one stop to Gare de Lyon.
Keep your ticket with you, you need it to leave the station.
Take a look at the website "easyCDG"'s description and see if it helps clarify:
https://easycdg.com/rer-charles-de-gaulle-airport-cdg-to-paris-by-train/