Go to flightradar24.com, click on any active flight on the map, and copy the URL from your browser's address bar. It will look something like:
flightradar24.com/UAL123/3a4b5c6d
Paste the link into the input field on the FR24 Link tab and click Fetch. The tool will pull the flight's origin, destination, aircraft type, airline, and registration automatically.
If the FR24 fetch doesn't work (the flight may have landed), switch to the Manual Entry tab. Enter the ICAO airport codes (e.g. KJFK, EGLL), aircraft type (e.g. B738), and optionally a flight number and route.
Want to fly a different aircraft than what's on FR24? Toggle on Override aircraft type and search from 150+ aircraft in SimBrief's database. Type an ICAO code (B77W) or name (777) to search.
Enter your SimBrief Pilot ID to load your saved settings. You can also set an alternate airport, cost index, cruise flight level, and passenger count. Leave any field blank for SimBrief to auto-calculate.
Click Generate OFP via SimBrief. This opens SimBrief's dispatch page pre-filled with all your flight parameters. Review and click Generate on SimBrief to get your full Operational Flight Plan.