If you want to install one of these packages, first you need to enable the repository in your system (dom0 and/or templates). This can be done by installing the `qubes-repo-contrib` package. This package includes the repository definition and keys necessary to download, verify, and install [QubesOS-contrib] packages.
The new repository definition will be in the usual location for your distro, and it will follow the naming pattern `qubes-contrib-*`, depending on your Qubes release and whether it is in dom0 or a TemplateVM.
For example, in a Fedora TemplateVM on Qubes 4.0, the new repository definition would be: