set the outputpath and assemblyname appropriately to point at the correct...

hello every body, please help,
when i compile my project it gives me this error:
"C:\users\Craig\documents\visual studio 2008\projects\sqrroot\sqrroot\bin\Debug\sqrroot.exe' is missing.
please build the project and retry, or set the outputpath and assemblyname appropriately to point at the correct location for the target assembly."

it gives me also the errors list:
"The type or namespace name 'NegativeNumberException' could not be found (are you missing a using directive or an assembly reference?"
---------------

here is my code of sqrroot.cs:

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace sqrRoot
{
public partial class sqrRoot : Form
{
public sqrRoot()
{
InitializeComponent();
}
protected override void Dispose(bool disposing)
{
if (disposing)
{
if (components != null)
{
components.Dispose();
}
}

base.Dispose(disposing);
}

static void Main()
{
Application.Run( new sqrRoot() );
}

// computes the square root of its parameter; throws
// NegativeNumberException if parameter is negative
public double SquareRoot( double operand )
{
// if negative operand, throw NegativeNumberException
if ( operand < 0 )
throw new NegativeNumberException(
"Square root of negative number not permitted" );

// compute the square root
return Math.Sqrt( operand );

} // end class SquareRoot

// obtain user input, convert to double and calculate
// square root
private void button1_Click_1(
object sender, System.EventArgs e )
{
Label1.Text = "";

// catch any NegativeNumberExceptions thrown
try
{
double result =
SquareRoot( Double.Parse( TextBox1.Text ) );

Label1.Text = result.ToString();
}

// process invalid number format
catch ( FormatException notInteger )
{
MessageBox.Show( notInteger.Message,
"Invalid Number Format", MessageBoxButtons.OK,
MessageBoxIcon.Error );
}

// display MessageBox if negative number input
catch ( NegativeNumberException error )
{
MessageBox.Show( error.Message, "Invalid Operation",
MessageBoxButtons.OK, MessageBoxIcon.Error );
}

}

} // end class SquareRootTest
}

and here is my code of NegativeNumberException.cs:

// Fig 11.4: NegativeNumberException.cs
// NegativeNumberException represents exceptions caused by
// illegal operations performed on negative numbers.
using System;

namespace NegativeNumberSquareRoot
{
/// <summary>
/// NegativeNumberException represents exceptions caused by
/// illegal operations performed on negative numbers
/// </summary>
class NegativeNumberException : ApplicationException
{
// default constructor
public NegativeNumberException()
: base("Illegal operation for a negative number")
{
}

// constructor for customizing error message
public NegativeNumberException(string message)
: base(message)
{
}

// constructor for customizing error message and
// specifying inner exception object
public NegativeNumberException(
string message, Exception inner)
: base(message, inner)
{
}

} // end class NegativeNumberException
}