You can select a person to search for by clicking on that person's name. If you want to select more than one person in a window, hold down the control key as you click the name.
If a photo contains any of the people you've selected, it will be shown.
If any of these are selected, only photos taken at that location and of that type will be shown.
When checked, all of the people selected must be in the photo. Similar for all of the locations and types.
If you did not get photos from all the years you selected, that means there were more photos than 500. Cut down on the number of years to get the rest of your photos.
For any given query, you'll be limited to 500 photos.
Your query will remain active for about a month, after which it will be deleted.