It wasn't working the other day so you may have to use the French rail site which is http://www.sncf.com
Since you are studying there, I assume you can read the French and the latter web site might be easiest for you.
Montpellier is a university town so you will have plenty to do. You can also type the city name into the VT search window above and get specific information.
Montpellier to Paris
The train would be your best option. Here's the French railroad site in English.
http://www.voyages-sncf.com/dynamic/_SvHomePage?_DLG=SvHomePage&_CMD=cmdHomepageUK&WB=HP
It wasn't working the other day so you may have to use the French rail site which is http://www.sncf.com
Since you are studying there, I assume you can read the French and the latter web site might be easiest for you.
Montpellier is a university town so you will have plenty to do. You can also type the city name into the VT search window above and get specific information.
Enjoy your trip.