Chick if entered a helicopter

Hi I am working on a game, which is based on the Unity Bootcamp Demo. I have made some Helicopters, which you can use to fly. I already have made a Helicopterflyscript. Now the QUESTION: How can I send a message to a other client, that he knows, that I have entered the Helicopter and he can change the Mesh of the Soldier to a Helicopter? Thanks for Answer Merlin Woff