Please give some more details of your travel plans and the questions you have. Then it will be easier to get advice.

Bom dia. I think you confuse pass (just an empty thing) and the trips/journeys separate or maybe try to do (most common mistake by newbees) REServ far too early-in most cases only MAX 2 or maybe 3 monthes advance. IN autumn (as that is the time you seem to think of) you do not really have to fear about ´full´ness that long before.

Hello, as requested I´m giving more details. I`m travelling in October to Europe, I intend to travel to diffent places, so I believe that a train pass is the best choice.

I need to book hotels in advance to get some good places.
To book the hotel I need to plan the trip and check day and time I´ll be at my destination.

I download an app on my mobile. I got the train times and even the maps.

When I enter the site to buy the train pass, I had to complete a file. The first question is:  where do you want to go. 

When I tried to write the name of the city, it simply did´t exist. So I could´t buy the ticket due to it.

In the planner there is the name of the city and the time of the train but in the website no.

I intend to go from Rosenheim (Germany) to Milan (Italy), in the app it´spossible even to see the map. In the site,  Rosenheim doesn´t exist .

That´s my problem. I can´t buy a train pass without beeing absolutly sure I can go to the places I´m planning to.

Rosenheim is no problem, regardless of what any maps shows. And October is outside of the tourist season so generally no problems to book reservations where needed. It's even a bit early for most trains to book.