Why No such file or directory: 'focal-custom.tgz'

Hi!

I do it step by step fellow Creating a custom Ubuntu image (snap/2.8/CLI) ,but output is:

    root@vivodo-3:/tmp/work# maas admin boot-resources create name='custom/focal-custom' title='Ubuntu 20.04 Custom Image' architecture='amd64/generic' filetype='tgz' content@=focal-custom.tgz
    usage: maas [-h] COMMAND ...

    optional arguments:
      -h, --help      show this help message and exit

    drill down:
      COMMAND
        login         Log in to a remote API, and remember its description and credentials.
        logout        Log out of a remote API, purging any stored credentials.
        list          List remote APIs that have been logged-in to.
        refresh       Refresh the API descriptions of all profiles.
        init          Initialise MAAS in the specified run mode.
        config        View or change controller configuration.
        status        Status of controller services.
        migrate       Perform migrations on connected database.
        apikey        Used to manage a user's API keys. Shows existing keys unless --generate or --delete is passed.
        configauth    Configure external authentication.
        createadmin   Create a MAAS administrator account.
        changepassword
                      Change a MAAS user's password.
        admin         Interact with http://localhost:5240/MAAS/api/2.0/


    [Errno 2] No such file or directory: 'focal-custom.tgz'

why? thank you!