how can i make an Game Opening Screen for pc game?

how i making in unity3d an Game Opening Screen for a pc game that i wanna build?

I believe you simply create a new scene and then use UnityGUI to create the interface elements.

You could use a static image as the background or, the way Will Goldstone does it in Unity Game Development Essentials: duplicate a scene from your game (a low poly version would probably be best), then use UnityGUI to create the buttons on top of it.

You can also use GUI Texture and GUI Text objects but UnityGUI is newer.