Although Photoshop Elements 12 enables you to crop your images as rectangular shapes, the Toolbox -- accessible in Expert mode -- features the Elliptical Marquee tool to help you select a round area.

For those who are using Photoshop Elements, you actually have a really quick way to add a vignette to an image via the Guided Edits panel. All you need to do is click on 'Guided' from the top menu and ...