Yes—use either the built-in Guided Edit vignette, or make one manually in Expert mode for more control.

A simple manual method in Elements 11:

1. Switch to Expert mode.
2. Use the Elliptical Marquee Tool to draw an oval or circle over the main subject.
3. Adjust it with Select > Transform Selection if needed.
4. Choose Select > Inverse so the outer area is selected.
5. Feather the selection to soften the transition.
6. Fill the selection with black, gray, or white using Edit > Fill Selection.

For even more flexibility, use an adjustment layer:

• Add a Levels adjustment layer.
• Paint on its layer mask so the edges/corners are affected and the center is protected.
• Blur the mask to make the vignette soft.
• Then adjust the Levels sliders to control how dark or light the vignette becomes.

If you want a faster option, Elements 11 also has Guided Edit > Photo Effects > Vignette Effect, where you can choose black or white, adjust intensity, and refine the shape.