Logan S

I'm making a Website. I am pretty new to this. My question is how do I have a CSS style sheet file separate from the html code files and still have the style apply to the html pages?
Ex. I go to this website http://www.freecsstemplates.org/ and download a CSS template but I can't figure out how to copy and paste it into notepad and have the layout displayed when I open it with a browser. When I try to open it in firefox, it is just a white page with the code written on the page.
And if I want the CSS and HTML in the same page, how do I get it to read the CSS. I tried typing
<style type="text/css"> and that didn't seem to work.
Any suggestions/tips?