@paul, when you put time slots on the Calendar, the shaded areas are the allowed times. The blank areas are blocked times. If you click the Text tab, you’ll see a list of time slots, like this:
03:00 am – 06:30 am
11:30 am – 03:00 pm
That means the web sites listed for the Calendar (or all sites if none listed) are available from 3:00am to 6:30am, then again from 11:30am to 3:00pm.
Also please note that you enter sites, i.e., domain names or partial domain names here. So “http://” or “https://” are not needed. For example, yahoo.com covers all yahoo domains, such as mail.yahoo.com, finance.yahoo.com, etc. If you enter edu or .edu (both are equivalent), it covers all domains under the .edu TLD.