How to make a reservation
First, make sure that you are added to the list of people who can use the calendar.
Create the meeting in your own google calendar, at http://calendar.google.com.
You must be logged in with your mail.huji.ac.il account, not any other gmail accounts you might have,
and you must be using google calendar (web or app) rather than outlook.
Click on "more options", then go to "rooms".
Open the building name to see the rooms in each building.
Choose the room you want to reserve.
If a room is not available for your slot, you will not see it unless you choose "include unavailable rooms"
If you have forgotten to ask for permissions for the calendar, you will also see the rooms as unavailable.
If you don't see the rooms in your google calendar, you are probably logged into your non-university @gmail account.
Use the account menu in the upper right corner of the window to switch to your @mail.huji.ac.il account.