superimpose or overlay vignette in V2 over V1

I want to do something pretty basic in Resolve that I've done before but i can remember how i did it. I'm a perennial beginner in resolve.
I want to superimpose a power window of someones face in V2 in a little oval that appears over the background in V1 . Actually superimpose is probably the wrong word because I want the face to completely replace the background image maybe, I should say overlay?
So: The background is on V1 and the image with the face is on V2.
- First I position the face using Transform in the Inspector on the Edit page.
- Then in the Color page I place a Power window around the face and adjust the softness.
- However here's where I'm getting stuck. I can see in previous attempts ( I did this about 6 months ago) that in the node where I added the power window the face is in an oval surrounded by black , and that works perfectly to appear over the background on V1. But i don't know how I did this.
- Instead of my node showing black around the power window, it is showing grey and that isn't allowing it to insert properly over the background. I've been looking at a bunch of tutorials but getting nowhere and I suspect its very simple.

Suggestions?

Lenny

You probably need to also connect alpha (light blue arrow on the node) to the output .

You get transparency outside the oval containing the subject, but if there is nothing in the track beneath it, the transparency will be black - that's probably what you did.

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Thanks Mario, I’m sure that’s true as the ones that are working do have the light blue line connected - But how do I do that ? Will that change the background in my node to black ?
Thanks

No. Transparent = black only when there's nothing underneath.

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Thanks again . I get that but how do you get that alpha line to connect . I tried to just
Grab with my curser but that didn’t work . Also will that background go transparent when the line is connected . I’m sorry if this seems really dumb .

You have to right-click in the node editor and add a new alpha output. Then you connect the alpha from the node to the alpha output.

Thanks Mario and Eric,
That does the trick.

Glad it's sorted out.