First download the package using npm or otherwise from observable.

import {Runtime, Inspector} from "./node_modules/@observablehq/runtime/dist/runtime.js";
import define from "./node_modules/@uwdata/data-utilities/index.js";
const runtime = new Runtime();
return new Inspector(document.body);

Here is how to insert the whole notebook

const main = runtime.module(define, Inspector.into(document.body));

Here is how to insert cells from the notebook into your HTML document. Suppose that cell is the name of the cell tha you want to insert in your HTML. First, make a div with an id like foo:

<div id="foo">

Then add the following to your javascript

const main = runtime.module(define, name => {
  if (name === "cell") {
       return new Inspector(document.querySelector('#foo'));
        }
        });