I booked through Booking.com and I need to amend my booking dates. How do I proceed?

I booked through Booking.com and I need to amend my booking dates. How do I proceed?

We do our best to facilitate amendments to bookings where possible. As you placed your booking in Booking.com, you will need to request a date amendment through your Booking.com booking correspondence or guest login. If the new dates are available, and the property owner is agreeable to the change, the amendment will be processed. If the dates are unavailable, or the owner cannot facilitate the change of dates, the amendment request will be marked as declined through Booking.com. 
If the rates are higher, you will have to pay the difference between the original price and the price for your new dates. If they are lower, the price difference will be reflected in your booking