Swiss travel pass problems

After you have selected your seats at the RhB site, you will see a box next the the spot where enter your birthday titled "reduction". Click on the drop-down button and you will see options "no reduction", "half fare travel card", "GA Travelcard". Click on "GA Travelcard", for which the Swiss Travel Pass is one type, and the ticket cost will be deducted leaving just the seat reservation fee.

Thank you Sam. Forgive me, what is the “Rhb site?”

what is the “Rhb site?

That’s just the site where you buy the Bernina seat reservations.

https://tickets.rhb.ch/en/pages/bernina-express

Rhaetische Bahn website, they operate the Bernina Express.
https://tickets.rhb.ch/en/pages/bernina-express

Thank you all so very much

I have gone on to the site and done this. It still looks like the price of a ticket from Tirano to Pontresina is 26 per person. Not that I expect any on you to be familiar with all costs, but Is that the cost for a simple seat reservation?

26 CHF is the cost of a seat reservation on the Bernina Express and the Swiss Travel Pass does not cover that. It is really a supplement for extra services, panorama cars, headsets with multi-lingual narration of sites along the way, wait staff going through the cars with drink carts and food orders.

I should add that if you don't like it, you can also travel on regular trains on the same route with no seat reservations, lots of room because service is so frequent and all the tourists are riding on the expensive Bernina Express trains. Also, the windows open so you can take better pictures of exactly the same scenery you see from the Bernina Express.

Sam, Give all this info and the fact that I may not even be doing the Panoramic trains,do you think the Swiss Pass still worthwhile?

Depends on what else you will be doing. The ticket cost of Chur to Tirano is 63 CHF 2nd class no matter what train you take. It is just that the Bernina Express has an additional 26 CHF seat reservation fee and is not covered by the Swiss Travel Pass.
Post your itinerary so we can take a look at it.

The Seat61 website lays out multiple options for riding the Bernina Express route at less than the going rate. Perhaps one of them will work for you:

Bernina Express tickets

With sufficient advance purchase, you can get a ticket for as little as €29.90. The ticket will not be flexible or refundable, however, and a physical ticket will be mailed to you from Germany.