FWIW, I downloaded your file, used the color picker to select the color of your ring, changed to the flood fill tool and modified the "opacity" to 30%, and filled the inside of the ring. Which worked. The opacity seemed a little thin to me so I made another at 45% opacity, and it looked pretty good to me. Try this and see if it gives the final product you are seeking.
You could use the same color as the ring for the partially transparent color, or any color you prefer
Here is 30% opacity:
![[Image: 8ORhJuc.png]](https://i.imgur.com/8ORhJuc.png)
And here is 45% opacity:
![[Image: 0NuNlUk.png]](https://i.imgur.com/0NuNlUk.png)
And then here is the image with 30% opacity superimposed over another image, just for example
![[Image: PbriWZD.png]](https://i.imgur.com/PbriWZD.png)
You could use the same color as the ring for the partially transparent color, or any color you prefer
Here is 30% opacity:
And here is 45% opacity:
And then here is the image with 30% opacity superimposed over another image, just for example