When you write HTML, it does not matter how you make 'line breaks' or move to the next line.
You could write in Notepad all on one line a mile long, or break to a new line after every word.
HTML will read it all the same. When displayed in your browser the page displayed will just break to the next line when it has to fit the page size.
An HTML page must start with this: <html> It tell's the browser this page is 'HTML'
The very end of the page uses: </html>

Next, if desired is the page title;This is what is displayed up very top left on the title bar:
<title>My Webpage!</title>

To make a page background color: <body bgcolor="green">
You can also use a 'hex' number, from a chart to represent colors, such as:
<body bgcolor="#00ffff"> (This color is 'Cyan').
Here is a hex color chart you can reference. (Will open in a new browser window).

Some commands, (or 'tag' is the proper term) for formatting text do what you want are as follows:

<br> Will force a break to the next line.
<p> Will start a new pargraph.
<blockquote> Will indent text.
</blockquote> Stops the text indent.
<font color="red"> Will change the font from the default black.
</font> Will end the font color change.
<i> Will make text in italics.
</i> Will end italics.
<b> Will make text bold.
</b> Will end bold text.
<u> Will underline text.
</u> Will end underline text.
<font size="+1"> Will make the font size bigger. Use any number up to 6.
</font> Will end the font size bigger.
<font size="-1"> Will make the font size smaller. Use any number up to -6.
</font> Will end the font size smaller.
<center> Will center on the page.
</center> Will end center on the page.

That's enough for now, next will be hyperlinks, then images!