How to use the Booking.com Calendar

Hi - I am trying to set up my account and am on the calendar page that says "When do you want your first guests to stay?". You are presented with a blank calendar, and when you click a date, it turns blue. Does this mean it is available to be booked, or that it is NOT available to be booked? 

Also, you seem to be able to click  only one date at a time (which makes me think blue means not available). There is no obvious way to select all days in a week or month or month at a time, such has holding down the shift key to select start and end dates, or the Ctrl key to select many at a a time that are not in a row. 

I need to know this so I don't set up an incorrect calendar. 

Ironically, there is a message on this page that says "it is important to set up your calendar correctly!", but there is no indication of what clicking a date and turning it blue even means.

Help!