Migrating Builds from TFS 2017 to DevOps Server 2022, a few questions...

Hi all,

We are going to be moving to DevOps Server 2022 and our on-prem build definitions will have to be converted to the infrastructure as code, YAML format.

The question(s) I have relate to getting started.  Currently, with TFS, I just choose New Definition, add/configure the steps or tasks and away the build goes.  With the new format, it is my understanding that the build definition is now a YAML script file that will be kept in source control.  How do I get started creating this file and where do I store it in source control, or is that all automatically done with a New Definition option?

Once I figure that out, I'll be recreating our Definitions with the Classic option for task configuration until I'm up to speed with YAML to script on the fly.

Any information or help is appreciated!  

Thanks!!