Paris to Trift Bridge

Lianne, that is a very obscure location, I had to look it up. According to Wikipedia (click here):

Reaching the bridge requires taking a cable car in Meiringen, followed by a gondola. Finally, a difficult 1.5-2 hour uphill hike leads to the bridge.

I assume by "gondola" they mean cable car, and not the boats you get in Venice!

So the question comes down to how do you get from Paris to Meiringen. I guess Meiringen is where you will be staying. You can look this up on the SBB (Swiss Railways) website: https://www.sbb.ch/en/
The route would be Paris Gare de Lyon - Basel SBB - Interlaken Ost - Meiringen and takes 5h45.
You can lookup specific times on the SBB website, there are multiple connections per day.

You can actually pre-book your tickets on the gondola from this website:

http://www.grimselwelt.ch/en/excursion-tips/trift

The gondola is small and only holds a very few passengers. The alternative is to hike the entire distance.