Hello @Linda1199,
The check in and check out on Airbnb works like it does for a hotel so you must specify April 2-13.
You enter a checkin date, in your case the 2nd of April, and then you're asked to enter a checkout date, in your case the 13th of April.
It can be a little confusing as accommodation providers like Airbnb and hotels work on nights rather than days. So you really pay for the night of a date rather than the day of the date.
Just like in a hotel, when you set the reservation to be April 2-13, you won't be charged for the 13th as you'll be leaving at or before the noon checkout time on the 13th. If you set the reservation as April 2-12 the host will require you to leave on the morning of the 12th as you won't have paid for the night of the 12th.
Steve.