You can put CSS information in a CSS sheet or directly in your HTML file.
Using a CSS sheet is generally the preferred method as it allows you to separate the styling from the content, making your code more organized and easier to manage. To link a CSS sheet to your HTML file, you can use the <link> tag in the <head> section of your HTML document like this:
```html
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" type="text/css" href="styles.css">
</head>
<body>
<h1>Hello, World!</h1>
</body>
</html>
```
Alternatively, you can also include CSS directly within your HTML file using the <style> tag in the <head> section like this:
```html
<!DOCTYPE html>
<html>
<head>
<style>
h1 {
color: blue;
}
</style>
</head>
<body>
<h1>Hello, World!</h1>
</body>
</html>
```
This inline method can be useful for small projects or when you want to apply specific styles to individual elements without creating a separate CSS file.