In terminal, use the following code to set the file and folder permissions:

chown www-data:www-data -R *          # Let apache be owner
find . -type d -exec chmod 755 {} \;  # Change directory permissions rwxr-xr-x
find . -type f -exec chmod 644 {} \;  # Change file permissions rw-r--r--

source: http://stackoverflow.com/questions/18352682/correct-file-permissions-for-wordpress