Include the snowfall.css file from the dist folder into your website or build it from the source with your own settings and add the snowfall markup. View the index.html file as a preview.
<head>
<link rel="stylesheet" type="text/css" href="css/snowfall.css">
</head>
<body>
<snowfall>
<snowflake><img src="img/snowflake.png">️</snowflake>
<snowflake><img src="img/snowflake.png">️</snowflake>
...
</snowfall>
</body>