Linked list problem while taking input

[Sam99]

Whats wrong here? The compiler says,

Data does not name a type.

Question: How can I add some info instead of a single value as a node in Linked List?
Please help. Thanks for any comment.

#include <iostream>
using namespace std;

class Course{
private:
      string title;
      string days;
      string time;

      Data value;
      Course *next;

public:
    Data input(Data item)
    {
        cout<<endl;
        cout<<"Enter course title: ";
        getline(cin, item.title);

        cout<<"Mention days for the course: ";
        cin>>item.days;

        cout<<"Mention time of the course: ";
        cin>>item.time;

        return item;
    }

		void add_course(Course *&head, Data x)
		{
			if(!head){
				head = new Course;
				head->value = x;
				head->next = NULL;
			}
			else
				return add_course(head->next , x);
		}
};

int main(){
	Course *head = NULL, A;
	Data item, n;

    item = A.input(n);
    A.add_course(head, item);

    return 0;
}

[MiiNiPaa]

Well, there is no type named Data defined anywhere. Ming tellying what Data is and how should we know about it in advance?