The Parallels provider is used just like any other provider. Please read the general basic usage page for providers.

When Parallels provider is installed it has a higher priority than any other provider shipped with Vagrant. In most cases you will not have to specify the provider name, just "vagrant up" will be enough:

$ vagrant init bento/ubuntu-18.04
$ vagrant up

But if you have a multi-provider configuration and/or want to be sure that exactly parallels provider will be used, then you can specify it explicitly:

$ vagrant up --provider=parallels