Jan 2, 2017 - 6:40 PM
Hello IviLeong1980, welcome to MySwissAlps!
The SBB website is mainly for Swiss citizens, so you won't find the tourist passes there. Their website is great for train schedules though, see here.
You will get part of the trip for free (to Wengen), and the rest is 25% discounted. Please see the Swiss Travel Pass coverage map.
Our Jungfraujoch ticket page provides a link to ticket prices at the bottom. If you wish, you can buy a ticket there too. But beware not to buy a ticket until you know the weather is good enough to enjoy the views.
Options to buy the pass are listed here: myswissalps.com/swisst ravelpass/price. You can print it at home.