Where is the finder located?

I recently downloaded something from Safari onto my iPad3 and now realize I don't want it. Where do I find the file (it's not an app)?

Unless you specifically copied the downloaded file into another app it was only stored in a Safari temporarily.

When you save a picture, it automatically goes to the Camera Roll in the Photos app. All other file types require you to actually pick the app they are copied to. When you do so you that app will open and display the file, so it's pretty obvious when it happens.

Files are stored in their respective apps. There is no general Finder app or function where random files can be stored by themselves. With few exceptions apps can not directly access files from other apps.

Unlike traditional computers where the file is the focus (file centric, I call it), iOS is app centric. Apps are king, and files belong to the apps, which create, store, and export them.

There are some exceptions using third party cloud services, but that is something the developer does outside the iPad's internal file system.