exporting calendars

[guillermoora]

hi,
I am a user of zimbra, my problem is that I would like to export my agenda or others agendas that people have previusly granted me.

when I go at zimbra help mail, it gives me the next instructions:

1. Click the Preferences tab.

2. Click the Calendar tab. The Calendar tab appears.

3. Scroll down to the Import / Export area, as shown below

this third option doesnt appear. the area of import/export doesnt appear.

what can I do to export the calendars??
I need an answer really quick please help me