Firestick connection to my MacBook air

If you mean an Amazon Fire TV Stick, you can't, at least not directly. The HDMI port on a MacBook Air is output only. You'd need a video capture device supporting HDMI in, and I'm not sure even then that it would work.

Regards.

If you want to stream video from services like Netflix, Disney+, etc. to your MacBook Air, it may make sense to access those services directly (via a Web browser), bypassing the need to plug a Firestick (or other streaming device) into your MacBook Air.