With adding a new price for a room you enter the price value (€ 80,00) and a date (2016-01-06). AS an example I add two new prices, (€ 100,00 / 2016-04-01 and € 120,00 / 2016-07-01).
These three prices create the following price information in the calendar.
From 2016-01-06 till 2016-04-01 the price for the room is € 80,00.
From 2016-04-01 till 2016-07-01 the price is € 100,00
From 2016-07-01 on the price is €120,00
This is how it works for the day prices. The other prices (week, weekend, mid-week) works the same but the moment the new price is valid is on the last day of the week.
Does this answer your question?
Regards,
Jan