open a file

Hello:
I have a simple question.
I know VC++6.0 MFC DOCument can auto open
a file use:
Void MyDoc::Serialize(CArchive& ar){
if(ar.IsStoring())
{
ar>>m_n}
else{
ar<<m_n}
}
But I need open a data file and read it from head to end.
and one word(EX."a" or "b"...).I know use c is easy.But VC++6.0
MFC??
Would you help me?
Yoh-Hei

You could use 'CFile' or a 'memory mapped file'

Hello:
But "CFile" or "memory mapped file",I don't know
how to make code in VC++6.0 MFC?How to start?