Layer Mask w/ Gradient tool...

How do you make layer masks with the gradient tool. I'm reading a tutorial and it says... "To fade the edges, I added a layer mask and used the regular gradient tool to fade the left edge." Here is the tutorial I am looking at: Click Here

Look at step 5 and step 1

create a new mask for your layer

set your foreground and background back to default colors

Drag your gradiant so that the black of the gradiant goes on the left edge, then make the line as small or big as you want depending on how much of a fade you want. (the smaller the gradient line the more the image shows, the bigger the line the more it fades out.

whenever i've done that (gradient with mask) it only fades the top of the image when i only want the middle portion, how do i fix that? i can post a pic if needed

Set your gradient to reflected gradient instead of Linear... or set it to radial if you want your center to be a circle