It depends on what you're doing with HP Quality Center. If you only have test cases and not requirements it might be as simple as doing export/import, but I'd recommend you reach out to your local account team and ask for assistance. Some customers prefer to use one of our integration options, and there are at least three ways to do that: (1) TaskTop, (2) OpsHub, and (3) the direct integration. An integration might be the best first step to an eventual migration.