How to use CSS to color the background of a website a color?

Link To Code:

I tried doing the following code, and it didn’t work, any thoughts on doing this?

The “correct” way to do this:

    background-color: #006666;
<body class="mybackground">

But note that on CodePen the HTML tab is meant for everything inside the <body> and the CSS tab for everything inside <style>.

I see, didn’t background-color correctly. Thanks for the help!