Mfc..how to change font of string with menu button

I need some help.i want create menu button to change font of CString displyed in main window.
We can see string "SAMPLE",and when i press menu button that i created i want to string "SAMPLE" to display with difrent font,i alreday created CFont object and added italic style with CreateFont;


this is my menu function:and CString m_text and CFont font1 are declared in FesbDoc.h

ON_COMMAND(ID_EDIT_FONT, &CFesbView::OnEditFont)

void CFesbView::OnEditFont()
{
CFesbDoc* pDoc = GetDocument();
::::WHAT TO ADD HERE:::::::


Invalidate();
}
Thanks.