Constructor in C# asp.net

Constructors enable the programmer to set default values, limit instantiation, and write code that is flexible and easy to read.
You can find very clean and deeply study of Constructors on MSDN.
Using Constructors
Constructors (C# Programming Guide)

A constructor in a class is a special type have the same name as the declaring class.
It prepares the new object for use.
It differs from a method in that it has no explicit return type.
Using overloading the constructor in that there can be more than one constructor for a class.
Constructor creates objects in a special memory structure called heap for reference types.
Value types (such as int, double etc.), are created in a sequential structure called stack.
Constructors cannot be synchronized abstract or static.
Example

public class CC
{
    private int a;
    private string b;

    // Constructor
    public CC() : this(42, "string")
    {
    }

    // Overloading a constructor
    public CC(int a, string b)
    {
        this.a = a;
        this.b = b;
    }
}