Purchase train tickets with Railcards Travel for Two

You got it.
When buying tickets choose the option ,Add Travel Card
You will be able to collect from the ticket machine at the station assuming you are using a decent sized one.
Buy the Two Together at the station. You need passport sized photos, again check the station facilities online most large stations have photobooths.The pass is issued over the counter to you
IMPORTANT bit, you must have the Two Together with you when trying to use your discounted train tickets, if not,at best you will be made to pay the excess,more likely new tickets

Richard,

Thank you for you help.

I understand your response except for "When buying tickets, choose Add Travel Card." For example, when I look at the site for the train tickets for travel between Paddington and Moretin-in-Marsh, I see under "Additional Options" Travelcard. Since our London hotel is near Paddington, we'll walk to the train station and won't need the Tube. So, do we really need to add the Travelcard? By the way, when we are in London on other days, we were thinking that Oyster Cards might be a good way to get around and see the local attractions.

John

You are right,its optional.
Oyster is likely a good option even for a few days as it caps fares in zones 1-2 where most of the attractions are to £7. The paper zone day ticket 1-2 was abolished this Jan. The paper ticket now is £8.90.(zone 1-6)
I should have said when buying tickets there will be an option to add Train Card. Then there will be a menu with the Two Together amongst others on it.

Thank you so much for the clarification. We'll probably buy our tickets this "afternoon." (I notice that it is already afternoon in England, and 50 F (10 C) in London. ) Enjoy your day. You have made ours more pleasant. Cheers.

John