Make a transicion scene

How can I make a transition scene in an online game?
In an online game there is a lot of people so if they are all in a same place this will cause lag, so I need a way to go to different parts of the map/world or whatever without making them go out of the game. I don’t know much about C# or unity 5 but I have the idea more or less, maybe using something like an invisible layer or wall that when an user trespass it, it will automatically send him into another part of the map. (I don’t know if I explained well)
Thank you very much.

Hi, there is several tutorials on the net that you can follow to get more familiar with networking and unity.

Here is one on Unet to give you a quick understanding :