[horde] How can i use calendar sharing?

[Pyi Phyo Kyaw]

I'm looking for a solution how can I set up the calendar sharing function In
Horde Groupware 5.1.1 webmail. I would like to share the schedule of our
company staff with our private group of email user. I searched on the
internet and calendar sharing function is for that case. But I can't set up
the sharing function because there is no sharing tab in my webmail calendar
and this is different from what I found on the internet. I sent you the
difference with the photos and I hope you would able to solve my problem.