HELP!

I have two classes,

class Classone : public CDialog
{
private :
CStrings etc...
void stop();
Public :
other stuff ();
}

class ClassTwo : public CDialog
{
private :
CStrings stuff, etc...
public :
ClassTwo(const char *pFileName, CWnd* pParent = NULL);

protected :
afx_msg void OnStart();
}

How can I call OnStart() from Stop() ????