Today I learned a new way of vignetting a photo in Photoshop (and I also learned how to pronounce vignette). I initially tried by going to Filter>Camera Raw Filter and editing the vignette setting there, but what I found was that it only allowed me to make the vignette either black or white, depending on how extreme I made it. My goal was to create a transparent vignette around my photo, so after asking my instructor for advice, I discovered how to do that; it just takes a couple of extra steps.
I started by using the marquee tool to select the part of my image that I wanted to add a vignette to. Once it was selected, I went to Select>Modify>Feather. Here is where you decide how many pixels you want the feather radius to be. After hitting OK, you click SHIFT+CMD+I to reverse the selection and then hit DELETE. Now you should be able to see your image successfully have a transparent vignette around the selection that you created.