Beginner friendly instructions on baking vertex colour from one object to texture of another?

Hello, I am still learning blender, so I need some guidance on where to go next with my learning on this topic.
I have a high res model with vertex colours, and I managed to retopologise that. But I want to put both the detail and the colours of the old model onto the new one, roughly. I was planning to somehow project it onto there.

I have not yet seen any tutorials on baking that I have enough knowledge to understand yet. I have tried to google baking vertex colours, but I am unable to follow the instructions, either because they are from 2013 etc or since they are way over my level, so I’m wondering if there is some beginner friendly videos or advice I should look at before I go further into this subject matter. I was able to texture paint already so I get the principle of a UV unwrap but baking is still mysterious to me and how to do it. And I barely understand the node system for textures. Now I just get error messages when trying to press the bake button following the old instructions.

If you’ve looked at a few, and tried to follow along, and been flummoxed, then nobody here is going to do any better.

Follow along with a tutorial. When you get stumped by something, stop, come here, link the tutorial with a timecode, show us some pictures and give us some words explaining where you’re having trouble, and we may be able to help you understand that part better-- after which, you can resume the tutorial, and maybe repeat as needed.