Confused since iPhoto to Aperture to Photos migration

I have been through several upgrades recently starting with upgrading from Mavericks to Yosemite to El Capitan. I had many years ago switched from using iPhoto to Aperture so all my photos were stored in Aperture. In the import from iPhoto to Aperture a folder was created within Aperture called iPhoto Library. I created many new Events in Aperture over subsequent years and when I migrated to Photos with Yosemite and now El Capitan I have iPhoto Events within which is iPhoto Library. Within iPhoto Events there is even a folder called From MobileMe! How should I be organizing all of this now? I have tried to move Events and seem only to be able to do so one event at a time. I am dragging them one at a time since Photos won't let me select more than one at a time. I think that I wasn't using Events and Albums efficiently before. I am open to suggestions but my primary concern is to get rid of the nesting of nested folders/events!!