The web is full of information on EU history; here are just a few pages that are quite good.

General EU history sites

Early post-war period

Pages with photos and videos showing hard times in Europe
www.dhm.de
www.trumanlibrary.org

Historical bases of European integration

The OECD in more detail
http://www.oecd.org/document

The first treaties
www.europarl.eu.int/factsheets

Developments up to the Single European Act
www.europarl.eu.int/factsheets

The Maastricht and Amsterdam Treaties: prospects for the European Union
www.europarl.eu.int/factsheets

The Single Market Programme & EEA
europa.eu.int/comm/internal_market
europa.eu.int/comm/external_relations

Communism’s creeping failure and spectacular collapse
www.zum.de
www.historywiz.com