This is all documented in the manuals.
In short:
You need to install the QC connectivity for QTP add-in on the QTP machine. It enables your QTP to access stuff stored in the QC project, and allows tools to execute QTP tests.
One such a tool is QC if you install the QTP add-in for QC. It enables QC to host (integrate, store) QTP tests, to launch QTP directly, and to schedule and perform QTP test executions from within QC´s test lab.
If you want to use version control, you need (as far as I remember) the appropriate QC feature option installed (additional license cost).
Be prepared that older versions of QC do not integrate well with newer versions of QTP, and vice versa.
Also, each .0 release of QC/QTP usually is imperfect in terms of integration, usually HP needs one or two patches before it works.
It is highly recommended to try this integration only if you have an active maintenance agreement since there are a lot of details to be accounted for.
(And sorry I am not 100% sure which of the add-ons is called add-on, and which is an add-in, but hey...)