Take the last instrument to represent an ellipse of white color. Fill 8% on the layers.

Apply now a different instrument

to draw an element colored in
AC3E03 with the parameters from the next picture.

Blending Options-Inner Shadow
Copy this new represented layer and place it out the same way it is indicated below.

Apply the previous instrument

and represent an element colored in
AC3E03 with the sizes shown next step.
Blending Options-Inner Shadow


The final result is this one!