Windows VM with Virtualbox and Packer

Hello, i am new to Packer and want to automate a Windows 10 VM under Virtualbox.
My problem is how to do it?
I have been clicking through guides and templates an the documentation, but it is really confusing. They all have settings they never explain what it does or is it nessecary. Or they just telling it was copying from other sources without any explanation.
Can any body help me where to start?

have you seen the learn platform?

In addition you can search Github for HCL2 or JSON files built for packer.
So maybe this helps you too.