a little help or a good explaination please

// Purpose: To fade out a white texture when transitioning into the game
#pragma strict

// Texture to fade out of view
public var theTexture : Texture2D;

// Create a private float variable that will store the starting time of when the level has loaded

function OnLevelWasLoaded(level : int)

// Set your starting time variable you created above to the current time of the game when it was loaded
// You can access the current game time with the following call:
// Time.time

function Update () {

// Fading out the white texture so that you get a transition of when you start the level
// Check to see if the current game time subtracted by the start time is greater than or
// equal to 3, refer to the BatteryCollect class in this assignment for good examples of if checks
// If so, then Destroy the local gameObject
// This is done by calling Destroy(gameObject)


function OnGUI()

// Use the private floating variable above and subtract it from the Time.time variable in the
// Lerp function here
// Uncomment the code below, making sure you include your variable being subtracted below in order for this
// section to work correctly

//GUI.color = Color.white;

//GUI.color.a = Mathf.Lerp(1.0, 0.0, (Time.time /* - your variable */));

//GUI.DrawTexture(Rect(0, 0, Screen.width, Screen.height), theTexture);

Wow this is asking for more than “a little help”. If you’re just asking for code to be written for you, it’s not what this is really for. What you want to look at though is shaders and writing your own. You can find all the information on those here Shader Manual

What you’ll need to do is create a variable in the shader, preferably one that gives you a slider on the inspector so you can test things easier. Then you need to do the Lerp separately from another script on the shader.

Check this answer