Why don't you try it by trial and error. You will learn a bit about how css works if you do it that way. Here's a page on font properties - http://www.w3schools.com/css/css_font.asp
I think you should fix your css before you go trying to change it. You have an extra } in there (they always comes in pairs - a { and then a } ) and there is no property called "change font".
And, if it doesn't work under one, try another.
(The code/html/php tags are to the right of the quote button.)