Hi
You did well looking at Thalys as it really does not make sense to fly. But I am not sure I understand your problems. You simply need to book (1) , Paris-Brussels (right now they are running a special, single fare of €35), (2) Brussels-Amsterdam and (3) Amsterdam-Paris.
Thalys uses Paris-Nord, Bruxelles Midi/Brussel Zuid and Amsterdam Centraal stations. Paris-Brussels is (generally) non-stop and takes 1h22; I am not 100% sure of the other timings but you can certainly find all the info online.
You can also book on
www.voyages-sncf.com, or
www.sncb.be or
www.ns.nl.