is there a css code to enable a user to click a link and bookmark the page? or is it only for javascript?

 

CSS is just for styling (Cascading Style Sheets), it doesn't do any functionality.

 

So in answer to your question; No, just javascript (not sure if there's php, asp methods though).

 

Looking at the broader picture, I would not waste space on your website with 'bookmark us' type links - it's very old fashioned and if someone wants to bookmark your site they'll do it via the browser.