How to properly use CURL POST with file input? Need help! or What's the correct syntax for CURL POST

Thanks everyone! The `-v` flag showed a 403 error—turns out I needed an API key header. Adding `-H "X-API-Key: mykey"` fixed it!

Also, the `--trace-ascii` tip was gold for debugging.

One last Q: How do I handle binary files like PDFs? Same syntax?