Here is the code:
body {
background-color: blueviolet;
}
<!DOCTYPE html>
<html>
<head>
<title>CSS Practice</title>
<link href="Sheet.css" rel="Sheet">
</head>
<body>
<p>
That is a Test For You
</p>
</body>
</html>
But when I load the HTML I do not see the change that CSS should make, I could not find a solution for that.

rel="stylesheet".cssis in the same directory as the.htmlfile. If that isn't the case, try changinghref="./Sheet.css"