From your Siberian installation folder, in the folder “app” there is a folder named “local”.
This Folder has been created to allow you to put your modified files here so they won’t be overwritten when you update your Siberian.
To put a file in app/local/, you have to use the same path as in the original folder. For example, if the original file is in app/sae/design/desktop/flat/template/, you should put the file you have modified in app/local/design/desktop/flat/template/.
Please note that you will have to update the modified files to make them being compatible with our updates.