first of all let me give you this precious advice: wait the new XS version is coming out in few days.
In new XS version the Update file has been rewritten, so updates should run smoothly.
But if you can't wait the new release... here you are...
Remember that update_to_xs2.php
MUST be run before uploading all XS files (you must also be logged in as administrator).
Another thing to remember is that your FTP client should be set to overwrite all existing files, so to be sure that old files are replaced by these new ones.
Finally, for people who feel more confident about their skills, I suggest to (after having performed a full backup of course):
- Login as Admin
- Upload update_to_xs2.php
- Run update_to_xs2.php
- Use an FTP client to remove all files and folders, except:
- Upload all new files (except config.php)
- Reapply the correct permissions to files and folders as listed in readme_english.html
- Enjoy XS
With this procedure, you will have a clean XS installation, having removed all unused files from older versions.