Can I ask something? To create a multiplayer game i have to use unity 4.6 or unity webplayer? Thanks in advance,
I'm not sure if I understand your question. You can use any version of Unity and any target platform you want to create a multiplayer game.
you should use unity to create game, and then you can choose for what platform you will build your game
You can create a networked game in any version of Unity and as Ryiah says, the Web Player is a deployment option. Although if this is your first project, networking is not something you should delve into just yet. P.s. Please title your threads with something that is relevant to the subject.
Yes, webplayer means to compile your game to play in a web browser; it does not mean a version of Unity 3D created with build-in networking like might seem logical. Unity does have build in networking that can be used for games and they are also making that easier to use in Unity 5, but Unity 5 won't be available until later. Unity used to have a very simple example Unity networking project on their web site called Star Trooper but although that's now in the asset store I don't know if that's still the project with Unity networking or if Unity removed the Unity networking.