You add the trains as journeys to the app, and then just before boarding the trains, you created the QR code, which is your ticket. No reservations are possible from Mulhouse to Basel. On the Swiss trains from Basel to Zermatt reservations are unnecessary. Trains are frequent and there is normally no problem to find seats.

If the planner says no reservation required you simply add the train to each of your trips and activate the grey slider to add them to your passes. They will then be added to the list below the QR code for that day. You do not have to buy any tickets for any train in the pass network - just reservations (or a few supplements) if mandatory (or for trains with optional reservations such as the German ICE trains).

If in doubt just list your train details in your post and the community will advise you.

Is this picture correct for adding trains to my trip? How to generate the QR code pls? Can I generate it earlier without using up days from my pass or I should only get the QR on day of travel? Thank you. 
 

You can generate a QR code after activating your pass. After activation, you'll see a switch next to each journey.

But it’s good practice not to activate in advance.

Great, tqvm