that code above is messed, buddypress forum keeps messing with my code?? not sure why? if you open the style.css in your theme directory you will see the code to import css files, but id suggest just add to the new code to your _inc/css/deafult.css file
You can put the html code in the header.php found in your theme folder, im not sure where you want it placed exactly so you will have to trail and error untill you find the right position.
The corresponding css code should be put in the _inc/css/deafult.css file, OR you could make a new separate css file and include this in your main css file like so