How To Edit My and information manually

Does anyone know where this file is located so I can edit it. If so, I'd greatly appreciate it.

Also, I got this error message when I tried to analyze my Bing SEO. However, I have a custom header and if I add anything it makes my banner look funny. Here's the message from bing.

The <h1> tag is missing.

Recommended Action:
Add a header to the page by using a <h1> tag and place it within the <body> of the page source. Example: <h1>A precise and descriptive headline for the page</h1>.

SEO Explanation:
The <h1> tag is an indicator to Bingbot and web visitors of what the body copy's primary theme or topic is. The <h1> tag reinforces the core keyword(s) found in the title, description, and the body copy. We recommend that the <h1> tag includes keywords that reflect the contents of the page and that it is not longer than approximately 150 characters in length.

If anyone can help me with this, I'd greatly appreciate it, since my SEO on this page is horrible.