To set up a private Cloudsmith repository for your Debian packages, start by creating a new project in the Cloudsmith dashboard and selecting Debian as the package type. Next, generate an API token to authenticate with the repository, then use this token to create a personal access token that can be used to manage the repository. With the personal access token, you can configure settings such as package visibility and permissions for users. You can also upload your Debian packages to the repository using the Cloudsmith CLI or API. Once uploaded, you can share the repository with others by generating a public URL or sharing it via email or messaging apps. To manage access control, you can add users to the repository and assign them roles such as package administrator or viewer.