Help with classes and constructors

class Salesperson 
{
   public:
Salesperson();						
~Salesperson( );						

Salesperson(double, double , double , double);  //????????

void getsales( );						

void setsales( int, double );	// set 1 of 4 quarterly sales. function will be called every time a sales figure is entered.  will also finds total annual sales.
 
void printsales( );           //called from main()
private:
     double sales [4];  // quarterly sales figures
};

//----------Implementation section

Salesperson :: Salesperson ()
{
   for ( int i = 0; i < 4; i++ )
      sales[ i ] = 0.0;

}

Salesperson:: Salesperson (double q1, double q2, double q3, double q4);  //??????
{
	a=q1;
	b=q2;
	c=q3;
	d=q4;
//???????????????????????
}

void Salesperson :: getsales ()
{
   double salesFigure; 

   for ( int i = 1; i <= 4; i++ ) 
   {
      cout << "Enter sales for quarter " << i << ": ";
      cin >> salesFigure;
      setsales( i, salesFigure );

   }
}

void Salesperson :: setsales (int quarternum, double total)
{ 	
if ( quarternum >= 1 && quarternum <= 4 && total > 0 )
      sales[ quarternum - 1 ] = total ; // adjust for subscripts 0-11

else 
      cout << "Invalid quarter or sales figure" << endl;   


   for ( int i = 0; i < 4; i++ )  // summarize sales results
      total += sales[ i ];
}

void printsales( )
{
cout << "Yearly sales are << total;    //??????
}

Salesperson:: ~Salesperson( )
{
	cout << "destructor took place";
}	
	
int main ( )
{
   Salesperson s, z(a, b, c, d);
   s.getsales( );
   s.printsales( );
   z.printsales( );
   return 0;
}