Each player starts with four colored train cards in hand and two tickets each ticket shows two cities, and you're trying to connect those two cities with a contiguous path of your trains in order to complete the ticket.
In more detail, the game board shows a map of Europe with certain cities being connect by colored paths. In general, players collect train cards, claim routes on the map, and try to connect the cities shown on their tickets. Ticket to Ride: First Journey takes the gameplay of the Ticket to Ride series and scales it down for a younger audience.