3d spotlight, how to?

Straight to the point, I'm using Davinci Resolve v. 15 and I can't get to create a spotlight.

I'll try to explain: I got a movie clip in Davinci timeline, then I go to the Fusion tab, there I see mediain and mediaout and everything's fine. Now, if I want to create a spotlight from the 3d menu, how can I link it to the movie clip?
Thanks!

What do you want the spotlight to do.
Like you say: it's in the 3D menu. Without 3D stuff to light, there is no need for a spotlight.
So instead of asking for a solution, please describe what you're actually trying to do, so we can help you better.

A spot light by itself won't do anything. It needs something to light up, a camera to photograph the lit object, and a renderer to convert the 3d scene into a 2d raster. I can't do better than to recommend reading the article I wrote about Fusion's 3d compositing system:

http://www.bryanray.name/wordpress/blac ... workspace/