To find it, you'll need to:
1. Consult your owner's manual: This is the best place to start. The manual should have diagrams showing the location of major components, including the starter.
2. Use a repair manual specific to your year and engine: A Haynes or Chilton manual (or a digital equivalent) will have detailed diagrams and instructions. You'll need to know the exact year and engine type (e.g., 6.0L Power Stroke, 6.7L Power Stroke, etc.) for accuracy.
3. Search online for diagrams and photos: Search for "[Your Year] Ford F-250 [Your Engine] starter location". You might find helpful images from forums or repair sites.
Important safety note: Working on a vehicle's starter involves working with a high-current electrical system. Disconnect the battery's negative terminal before attempting any work on the starter to prevent injury.