It is easy, just launch the app. A loading screen will show up. Just be patient and wait until it scans all folders and files for erased photos. It may take a while depending on how large your memory is. After searching is complet , it will show a new screen with folders, each folder contains pictures from a specific location. check them one by one looking for you photos, each folder contains a list of images inside it. Check images you want to restore and when you finish doing that hit restore button to recover them. Now a dialog will show up telling you in wich folder to find recovered images. You can either browse this folder or browse the gallery where you can find them as well.
Just press and hold on the image.
Can i use Unseen Gallery to recover deleted images?
You may,if you didn't use cleaner app after deleting the images you may find cached version of the deleted images and recover them.
No,just JPEG and PNG images for now
Does it support Samsung's Secure Folder
Yes, its fully supported.
Is it safe to delete any shown image in Unseen Gallery?
The answer depending on which app created this images and what it do with it,and you have the full responsibility to delete any image.
Sure, You can spread the word about the app or give good feedback and ratings.