Where should I hang blackout curtains for this window that has a small bench? And how long should they be?

The window width is 71" and the length is 81" from the top of the window box to the floor. Not sure if the blackout curtains should be hung on the wall surrounding the window or try to fit them inside the window box? And if on the wall, should they be floor length/how high do I hang the rod/should they puddle on the floor or graze? All the advice needed please!!