Validate error repairs

I utilized NU HTML Checker today. We cam up with quite a few errors. I was wondering how I can fix them within WordPress. I have basic HTML knowledge, but PHP is out of my realm just yet. Here is the link and a example: https://validator.w3.org/nu/?doc=https%3A%2F%2Fharleyoilcoolers.com%2F

Error: Element link is missing required attribute property.
From line 1209, column 1; to line 1209, column 201
=’all’ />↩<link rel=’stylesheet’ id=’js_composer_front-css’ href=’https://harleyoilcoolers.com/wp-content/the…es/ewa/vc/js_composer/assets/css/js_composer_front.css?ver=3.6.12&#8242; type=’text/css’ media=’screen’ />↩<link

Any help is much appreciated!