put class into dll is one of the questions that make me trouble utill one day
when I see <com inside>'s first chapter, I get the result.
and tried in dos cmd  and also VC6.
A:VC6
1:add a class like
student.h
class _declspec(dllimport) Student 
{
public:
 void setName(char* nameC);
 char name[10];
 char * getName();
 Student();
 virtual ~Student();

};

//
#include "Student.h"

Student::Student()
{

}

Student::~Student()
{

}

char* Student::getName()
{
 return name;

}

void Student::setName(char* nameC)
{
    strcpy(name,nameC);
}
2:oh,this is in a app of dll,not exe app project
and then just rebuild can create a dll,its contains
this class definition.(can read in *.lib by text).
3:use it.
write another head file:

class _declspec(dllexport) Student 
{
public:
 void setName(char* name);
 char name[10];
 char * getName();
 Student();
 virtual ~Student();

};
4:include this header in app use it and
set Project->Setup->Link ->L as firstDll.lib firstDllLib.lib
5:run and link ok can when in onDraw()
       Student s;
 s.setName("o00o");
 char* p;
 p=s.getName();
 CString temp;
 temp.Format("%s",p);
 pDC->TextOut(23,23,temp);
//----------------------------end of vc6.0---------------//