If you have opened or viewed a meeting room calendar in Outlook 2013, follow the instruction below to view it in the Webmail, otherwise you need to add the meeting room calendar in the Webmail first.
Sign in Webmail and switch to the Calendar View by clicking the calendar icon located in the lower left corner.
In the left navigation pane, click "Rooms" to expand it, check the meeting room that you want to view, the meeting room calendar displays side by side with your personal calendar.
If needed, close your personal calendar so you'll see more details in the meeting room calendar. You can add your personal calendar back by checking "Calendar" under "My Calendars". Please note, a request for a meeting room needs to be made from your personal calendar, see instructions on Make a Room Request in Webmail page.
If you have not opened or viewed a meeting room calendar in the Outlook desktop client on a PC, first you need to add the calendar:
In Webmail, go to the calendar view, then right click "Rooms" and select "Add Calendar..." from the pop-up menu.
Click "Name..." to open the address book.
In the left panel, click "All Rooms".
Type "library" in the search box and hit enter, you'll see a list of library rooms. Click a room to highlight it, then click "Select" to add it and click "OK".
Notice the room calendar has been added, click "OK".
You'll see the room calendar is displayed next to your personal calendar.
You'll only need to add a room calendar once. It'll be available next time when you sign in Webmail, but you may find it has been added under "People's Calendars" instead of "Rooms". You can drag and drop it over "Rooms".