Where to place my pictures from a harddrive

If you use the Photos app, do not remove the Photo Photo Library.photolibrary directory.

You can place the pictures you have on your drive in the Pictures folder. What I would do is create a new folder inside Pictures and place my image files in there.

You can use the Photos app to browse your library in the directories you placed in the new folder under Pictures. If you would like to not use the Photos dedicated library, you can remove that option in the Preferences of Photos under General > Importing > Copy items to the Photos library. Make sure iCloud Photos is deselected under the iCloud tab in Photos.