You need a URL address for that or upload your logo to codepen if that’s possible. You cannot add the logo locally from your pc straight to the code on codepen.
You could add a lego to your website using <img> tag (like you did)
But in src attribute you have to put a URL of your image as you can’t upload an image locally from your PC. (like @anon58011934 said)
You can upload your logo on this website, so you can get its URL https://postimages.org/