If events show up with the wrong time in the webapp at https://fruux.com/calendars, the timezone for the webapp is probably set incorrectly. The timezone can be adjusted at https://fruux.com/account/settings/. Once this is set, all of your events will be show in the local time for this configured timezone.

This setting does not affect your data in the system - only in which timezone events are shown in the webapp. If you e.g. have set up syncing with your computer and your phone and then travel from London to Sydney, the calendar apps on your devices should auto-detect the Sydney timezone and show your correctly - according to your local timezone in Sydney.