On my Windows 7 PC it is at the following location. c:\windows\users\your user name\appdata\roaming\adobe\lightroom\web galleries. You may have to create the 'web galleries' folder. The 'appdata folder is hidden by default. This can be shown by going to 'control panel >folder options >view, check 'show hidden files, folders, and drives. Or simply type 'appdata' in the search box.