How do I book an overnight stay?

I'm looking to book someone to housesit and look after my kitty for 3 nights, but when I try to send an enquiry to a sitter I have to enter the dates, as well as start and end times on each day. I obviously know the start time and end time of the whole three day period, but want them to be there throughout the rest of the time. Am I missing something?!

Thanks!