You will need to purchase the, 'Targeta Dorada' ( Golden Card ), to obtain the senior discount

You cannot purchase a Tarjeta Dorada without presenting yourself with ID at a station.
What makes you think a Tarjeta Dorada will be of any great value to you rather than advance purchase discounted point to point tickets? Have you read one the many guides on RENFE?
I do not not why are unable to see and click on 'Welcome' top of the RENFE first page.

You get English when you click "Welcome" in English on the Renfe home page, but it will still revert to Spanish for some pages that have not been translated. You do need to buy the Tarjeta Dorada upon arrival there, and in that case, you can buy some senior discount tickets at the same stop. Online booking may require a card number, which you would not yet have. Online booking works for advance discounts, which could be just as good or better than senior discounts, if you can navigate any Spanish that may come up. Plan to pay online with PayPal to avoid credit card issues.

You can only buy the Tarjeta Dorada card when you are in Spain. It costs $6 Euros and if you are here traveling on a train, it is well worth it. It gives you discounts on all the train fares. Sometimes though, a promotional fare is cheaper. It does create a problem trying to buy tickets online in advance unless you already have a TD card. They are good for one year.

The Renfe site does not really change to English. It is not easy to use at this point, but you can sort of figure it out. Pay for tickets using Paypal, don't try to use an american credit card. For some reason Renfe doesn't like those. If you have to, use freetranslation.com to translate each segment of the website, toggeling between the two. I have used the website quite successfully for many trips! Don't expect the site to change to easily understandable english, it doesn't!

The more advance purchase you can do, the better the price. Especially if you are traveling during the summer to popular destinations, the trains are filling up. I buy my tickets as soon as I know where and when I am going. So far, a few days in advance has been fine, but a few weeks is better.

Thanks, I'm glad I got more understanding info that the top reply.

Melva, interesting how some responses are just intended to remind us of how "dumb" we are, instead of actually helping us with our travel question. Overseas travel can be daunting enough without snide comments from those "in the know". I use these and other forums all the time and there is always the good, the bad and the......well good luck on your travels.