Can you be a little more specific?
First, set your base rate -- your monthly price -- under Pricing. If you want to set a price for someone staying a whole month, you can do it under Pricing, Long-term prices. It takes your base rate and discounts it by a certain amount.
To set prices for future months, go to your calendar.
Make sure you have run through your availability settings on the top right of the calendar page, especially "How far ahead can guests book."
(See below)
If you don't want any bookings until five months from now, block off your calendar until then.
Does this help?