How do I get my Lenovo computer to recognize my monitor speaker?

How are you connecting to the monitor? DVI / HDMI?

If you will look on your monitor you will find a hole where a cable goes for the sound and that cable plugs into your laptop you need to check that first cuz that's usually the way they work

With only "Lenovo computer" and only "monitor" and no details on connection cable type(s), there's no accurate help for you.
Wasted question.