How do you link a CSS document to a HTML file?

Both files need to be stored within the same folder. Once this has been done, within the <head> tags of your HTML file (the header), you will need to create a link to the CSS file.
This is done by using the <link> tag, as seen below:<link rel="stylesheet" type="text/css" href="filename.css">where filename is the name of the CSS file you wish to link.