To use and fix QuickBooks Tool Hub errors, first, download and install the tool from the official Intuit website. Open QuickBooks Tool Hub and select the appropriate tab for the specific error you're encountering. Follow the on-screen instructions to run the corresponding tool and diagnose the issue. The tool will scan and attempt to fix the error. Restart QuickBooks after running the tool to see if the issue is resolved. If the error persists, you may need to seek further assistance from QuickBooks support or consult a professional for expert guidance.