Как исправить ошибки?

#include <iostream>
using std::cout; 
using std::endl;
 
#include <string> // program uses C++ standard string class
using std::string;
 
// GradeBook class definition
class GradeBook
{
public:
   // constructor initializes courseName with string supplied as argument
   GradeBook( string name,tName )
   {
       setTeacherName(tName);
       setCourseName( name ); // call set function to initialize courseName
   } // end GradeBook constructor
 
   // function to set the course name
   void setCourseName( string name )
   {
      courseName = name; // store the course name in the object
   } // end function setCourseName
 
   // function to get the course name
   string getCourseName()
   {
      return courseName; // return object's courseName
   } // end function getCourseName
 
   // display a welcome message to the GradeBook user
   void setTeacherName(string tName)
   {
       teacherName=tname;
   }
   string getTeacherName()
   {
       return teacherName;
   }
 
   void displayMessage()
   {
      // call getCourseName to get the courseName
      cout << "Welcome to the grade book for\n" << getCourseName()  
         << "!\n" <<"Учитель этого курса"<<getTeacherName()<<endl;
   } // end function displayMessage
private:
   string courseName;
   string teacherName;
}; // end class GradeBook  
 
// function main begins program execution
int main()
{
   // create two GradeBook objects
   GradeBook gradeBook1( "CS101 Introduction to C++ Programming","Джигурда" );
   GradeBook gradeBook2( "CS102 Data Structures in C++","Онотоле" );
 
   // display initial value of courseName for each GradeBook
   cout << "gradeBook1 created for course: " << gradeBook1.getCourseName()<<"and Teacher"<<gradeBook1.getTeacherName()
      << "\ngradeBook2 created for course: " << gradeBook2.getCourseName()<<"and Teacher"<<gradeBook2.getTeacherName()
      << endl;
   return 0; // indicate successful termination
} // end main

GradeBook( string name,tName )

GradeBook( string name, string tName )

void setTeacherName(string tName)
{
        teacherName=tname;
}

teacherName=tName;