If you haven't done this yet, then create a train role play.
Re-create a train in your home.
Make tickets, dress up, be a ticket inspector, train driver, passenger.......
Watch video clips of steam trains.
Listen to sounds of trains.
What sights will you see?
What sounds can you hear?
Buy tickets, collect passengers at the station, set off on your train, look at the animals in the field.
Use your imagination.