How to transform a gradient within a layer mask

[Doc_Pit]

Hoping I can get some help with a masking problem.  Picture an image that contains several ripples, like when a raindrop lands on the surface of a pond.  Each ripple is essentially a series of concentric elliptical shapes emanating from the center, each ellipsis slightly irregular.  To each of these ripples, I would like to apply a graduated blur, so that the ellipses closer to the center are sharper than those further from the center.  One way to do that would be to convert the ripples layer to a smart object, apply a Gaussian blur, and apply a radial gradient to the blur filter’s layer mask.  However, I would like to shape (i.e., transform) the gradient to the contours of each individual ripple.  I understand there are ways to contour a gradient.  I can, for example, create a gradient in a shape layer and transform the shape.  However, I haven’t figured out how to contour a gradient within a layer mask.  Does anyone know how to do this?

[Trevor.Dennis]

Make the layer a Smart Object

Apply the blur

Make the shape you need in B&W and past it into the SO Mask.

Use mask properties to control the mask feathering.

If you can give us screen shots with more detail, then we can maybe help further if needed.

[Doc_Pit]

Trevor, thanks very much for your response.  Persuant to your suggestion, I need to follow-up my original question with some questions regarding copy and paste.  I made the shape and attempted to paste it into the SO Mask.  Instead of pasting into the mask, it pasted the shape onto a separate layer. 

I looked at two tutorials (Steve Patterson https://www.bing.com/videos/riverview/relatedvideo?q=how+to+paste+into+a+mask+in+photoshop&mid=856CB... and Julieanne Kost https://www.bing.com/videos/riverview/relatedvideo?q=how+to+paste+into+a+mask+in+photoshop&mid=A67B7... ).  Both address this issue.  Following their instructions, after copying the shape from its layer, I pressed the alt key (Windows) to reveal the mask; then I pasted.  In each of their tutorials, this successfully pasted into the mask.

In fact, I encounter the same problem even if I’m just trying to cut from one layer and paste into another w/o reference to a mask.  In the image attached, I tried a simple experiment. I created a  yellow rectangle on one layer and a smaller black rectangle on a second layer.  I then copied the black rectangle from layer 2 and pasted into the yellow rectangle on layer 1.  Instead of pasting on to layer 2, PS created a new layer, layer 3.  Moreover, the black rectangle on layer 3 does not align with the source rectangle on layer 2.

I also converted layer 1 into a SO, created a smart blur filter with a mask, copied the black rectangle from layer 2, pressed the alt key to view the mask, and attempted to paste into the mask.  There was no result at all.  Nothing was pasted into the mask.  No new layer was created.  Bottom line, as you suggested, I made a shape, but I was unable to paste it into the layer mask.

It seems ridiculously simple.  Can you see what I’m doing wrong?  Also, I reset Preferences to make sure the problem is not something flaky with PS.