Trains

Frankfurt to Paris, see shedule and book tickets at www.bahn.de or www.oui.sncf

Paris to Basel, see schedules and book tickets at www.oui.sncf or www.sbb.ch

For travel within Switzerland, use www.sbb.ch (can also sell you tickets from Switzerland to Italy)

go to the man in seat 61, all you seek is there. back it up with research on Rome2rio.

if you don't want to DIY, Rick uses Raileurope.

This is a much better website for schedule and fare information for
germany (and schedules for all of Europe) than Bahn.de (actually Bahn.de will probably get you here eventually; might as well start here.).

The link is basically bahn.de, unless I am missing something?

Bahn.de is a general website for the Bahn, and not in English, and you CAN get to the schedules and fares (query) page from bahn.de, but the link I gave, https://reiseauskunft.bahn.de/bin/query.exe/en IS the query page for the Bahn, in English. Why not go there directly?

If you visit bahn.de the first thing you see on the site (apart from the strike notice) is the "query box", enter the stations and the date and time you wish to travel and press "Suchen" and you will get suggestions. No need to go to a special query page. Using the main page is also a great place to find other information about the trip. Such as the onboard menu e.g.

And if you don't speak German, just use Google translate. Or click the small world map and choose another language.

The "bahn" page does appear in English if that is what you want. I use use bahn .de. That page is in German, as pointed out above.

https://www.bahn.com/en/view/index.shtml

is in English - saves a step

In fact just https://www.bahn.com starts in English. Same folks, easier to type