Not a basic question, we're always working to make BuildMaster as easy to use as possible, so getting feedback on how to improve our docs and tutorials will be great :)
If you haven't seen it already, we've recently updated our Azure DevOps Integration Documentation; there's a lot of content there, and we hope to continue to make it easier and include tutorials at some point.
Basically though, I recommend you start with Create New Application > Azure DevOps CI/CD. That will create an application with the Azure DevOps CI/CD Template, and you can see how a "full CI/CD" would work. It should just build "out of the box", and use our publicly-available AzureDevOps repository.
What your'e describing, it seems like just a small portion of that. Once you've got the manual process working, it's just a matter of creating a Git repository monitor. you can configure that to monitor the branches in your AzureDevOps repository.
https://docs.inedo.com/docs/buildmaster/ci-cd/continuous-integration/build-triggers/repository-monitors