Train to Yours/train station

Do you mean Tours? In most cases you don't need to know which station you need to depart from. You just choose something like PARIS or Paris-All stations as your origin, and the options supplied by the rail website will make it clear where you can board.

Most trains (and I think all the TGVs) for Tours depart from Gare de Montparnasse. There is an occasional, cheaper but slower, regional train from Gare d'Austerlitz.

Haven't a clue ---- Yours ??????? The best station is the one that the train leaves from.

I'm assuming Tours.
You have the choice between slow trains from Paris Austerlitz and fast trains from Paris Montparnasse. The fast one are much better, and not more expensive unless you travel last minute.
By the way there are two stations in Tours: Tours AND Saint Pierre des Corps. A train to Tours proper is marginally more convenient, but arriving at the other station is no big deal.

You'll want Montparnasse for High Speed Direct.