How do you take a train from Charles De Gaule Airport to Honfleur, France?
There are no trains to Honfleur. The closest you could come by train would be (I think) Deauville, where you could take a taxi or a bus. The trip to Deauville would be through Paris and take at best 3-1/2 hours. Driving would be quicker (and you'd want a car in Normandy), but maybe you don't want to do that.
As mentioned above, there are no trains to Honfluer. What is see is to take the Roissy bus to the Gare du Nord train station, transfer to the Saint Lazare train station and then take the train to Deauville. It will take 2-3 hours to get to Deauville. Here's a link to what I see. http://gyazo.com/2977f9a044b674f94e1a4257f01fae28
I have the idea that the Roissybus goes to Opera, not Nord. If that's the case, Metro 4 will scoot you up to Lazare in a couple of minutes. If you take the RER B in from the airport, you'll have to get off at Nord, tunnel hike to Magenta for the RER E to Haussmann, then hike some more to Lazare SNCF. Regardless of how you get to St Lazare, once you get to Deauville, it's the Number 20 bus (Bus Verts du Calvados) that goes to Honfleur. From the bus station it's about a five or ten minute walk to the old port.