Noise effect java script

Does anyone know how I make this effect on the background noise on my site by webflow?
see in this example:

Here is my site Read-Only: LINK
(how to share your site Read-Only link)

Try to use this library in your custom code section:

Thanks a lot!!!:grinning:

I’m not very good at websites … could you tell me how I put this in webflow?
What part of the code stays in the head and how do I do it?