An HTML page has a basic structure that pretty much always looks like the following. (This is just the basic structure, there is usually a lot more content, but this gives you an idea of the basic layout.)
The <!DOCTYPE html> tag should begin every web page. It tells the browser that this is an HTML (currently HTML 5) document. It's an example of a tag that doesn't have an end tag.
<html> and </html> show the beginning and end of the HTML document.
<head> and </head> is considered the header section of the document. It frequently includes the <title>Page Title Goes Here</title> of the page, which is what shows as the name of the window (or tab) in your browser.
<body> and </body> describes the body of your document - this is where all the content that you want displayed on the page goes. Right now, there is no content in the body, which is why the web page display on the right (Result) is blank.