It is a good idea to enter codes in logical segments. This will make it easier to decode/debug later on if you experience a problem. If all of your code is jammed together, it will be difficult to locate the source of any problem.
Code should be separated into segments by function.
Here is an example:
<html>
<head>
<title>This is the title</title>
</head>
<body>
<h1> My Information <h1>
<p>some text</p>
<h2> a sub heading</h2>
<p>some more text<br/>
2nd line of text </p>
</body>
</html>
The extra blank lines between the segments helps keep lines of code separated in the Notepad file, but the text will not display the separate lines in the browser.
The extra space on the left side of the <h1>, <h2> and <p> tags helps you spot any missing tag. As you gain experience, you will become more adept at entering code to make the task of decoding/debugging easier.