First Lady Laura Bush at podium, in front of seated audience, at the White House Conference on Global Literacy.
The former First Lady is at the podium for a conference.
First Lady Laura Bush being the wife of former US President is the former First Lady and her in front of seated audience means at the podium while for a (White House) Conference.
The White House Conference for Global Literacy is still a conference.
Barbara Bush used to be the First Lady.