Using a photoshop tutorial on youtube, I took one of my photographs from my summer project and tried two different vignette effects.
-Open the picture on photoshop
-Using the elliptical marquee tool create the oval shape starting near the edge of the picture.
-Right click, and then invert selection
-Create a new layer
-Fill the outer space using the bucket tool with black
-Go to Filter --> Blur --> Gaussian Blur
-Play around with the amount of Gaussian Blur until you are happy with the effect.
-Go to Filter --> Lens Correction
-Click on custom
-Then play around with the Vignette slider bar until you are happy.
I personally prefer the second effect, as I think that it looks more natural.