How to create a PLAY GAME GUI ?

I already have a scene for my character. All I want to know is How to create the GUI for my game that there is a BUTTON there named PLAY and when the moment i clicked the play button the game will start and call the scene where the game will be started?

Under Components you should find a GUITexture GameObject. Create one of those and attach your GUI to it. The buttons you can place on additional GUITexture GameObjects or if theyre attached to the main GUI, just create empty GameObjects and attach scripts with OnMouseDown().