We can use various libraries in the browser. To do so, you need to link to them.
Within your exercises folder, create a new folder called p5 which contains an assets folder which contains a css folder and a js folder.
body {
background: blue;
margin: 0;
padding: 0;
}
<!DOCTYPE html>
<html>
<head>
<title>P5 in the Browser</title>
<link rel="stylesheet" type="text/css" href="assets/css/main.css">
</head>