thanks for trying to post your code. The code you posted in the last comment though is HTML not CSS.
It looks like this exercise wants you to add some CSS as it says
The CSS width property is perfect for this. Create a new type selector in the style sheet that gives your div element a width of 300px .
If you are unsure what is CSS, look at the code provided in the exercise and notice how it is laid out and written. That is CSS. Here it is for reference again:
body {
background-color: burlywood;
}
h1, h2, p {
text-align: center;
}
The CSS language lets you target certain html tags and tells the browser that these tags need to be treated in a special way.
For eg. in the code sample you’ve been shown in the exercise, they are targeting the body tag because they want the browser to change the background-color of that area to something other than the default.