Step by step:
If you have enabled "Custom Web" within WeatherCat, you can specify an HTML Source Folder (Preferences > Custom Web > Main > Set HTML Source, mine is named "CustomWeb"). In this folder you have to put all files that should be processed by WeatherCat. You have to create an html file that contains the simple graphs, otherwise no graphs will be uploaded and you will see no graphs when you hover the steel gauges. Also the file "realtimegaugesWC.txt" has to be in this folder. Next you have to specify a Save Path folder (Preferences > Custom Web > Main > Set Save Path, mine is named "SavePath"). In this folder WeatherCat processes the html files from the HTML source folder, and the so created content of this save path folder is ftp'd automatically by WeatherCat to your webspace periodically. The period of uploads you can also specify in the above named Preference section. Now you only have to tell SteelGauges where the graphs are located on your webspace.
Additionally you should take a look in the UserManual page 87ff to get help creating Custom Web Pages.
Cheers,
Reinhard