Feb 25, 2017 - 9:31 AM
in reply to Priya
The SBB site is primarily geared to Swiss residents, not tourists, so they won't ask whether you have a Swiss Travel Pass. You can use the site for train schedules though. To buy tickets, the last link Lucas gave you shows all the options. You only need to buy a ticket from Domodossola to Milan. It's explained on the Swiss Travel Pass page here.
If you want seat reservations all the way from Bern, which is not needed, it's a bit more complex as most websites do not sell such "pass holder" tickets (partly free because of the pass, but with a reservation for the entire route). As you live in India you can visit the Indian site at www.raileurope.co.in#t ab3 and select your pass, class and route to find a ticket.
Is this what you are looking for?