We found friendly help at the Monorail
We must have looked very desperate and in fact we also were unable to find the right buttons to press in order to get a ticket for the Monorail. But that nice man who was in charge of supervising the station came out of his counter and explaned it for us. He did not speak any english, but we understood anyway.
You get your ticket and then you have to put it into a small machine that will open the bars for you when entering the Monorail-area.
The weblink below also has some instructions at least partly in english !