You may for one reason or another need to modify your reservation request.
If you want to change an accepted or pending reservation, first contact the host to notify them and to determine the details of the change.
Currently, the only way you can modify a reservation that you have already paid and submitted is to cancel it and make a new one that takes into account the desired changes.
Here's an article explaining how to cancel a reservation as a Guest.
Once cancelled, go back to the listing and simply complete a new reservation with the new booking parameters.
Please note that as we grow, we will provide more efficient ways to modify an ongoing reservation.