You MUST update a COPY of F1, so you can easily come back to previous version if the update is not successful.
You should disable your Extensions (INITs) before launching the updater, some anti-virus software can stop the updater.
After launching F1Updater you must choose the F1 application you want to update. After a few seconds the updater will show a message reporting the succesful (or unsuccessful) uptade.