There are hundreds of war cemeteries along the western front. To help you find a particular cemetery or grave, underneath mentioned sites are very useful;
The Commonwealth War Graves Commission (CWGC)
Search on name / cemetery / country (CWGC)
Find a grave
Here you can search on soldier's name, location and more
All English cemeteries in France, indexed on alphabet

English cemeteries in France

German war graves commission
Commonwealth WW1 military cemeteries in France
French WW1 battles