Can't add files to /Library/WebServer/Documents
I can't use my iMac as a local webserver because I can't add any files to /Library/WebServer/Documents. I was able to edit the index.html.en file after using the sudo and chmod commands in Terminal to grant myself read and write privileges to the file, but I still cannot save any other files to the same directory. Why not and what can I do about it? My operating system is Lion (10.7.5).