Forum:How do i change the font and/or size of the text on my navigation bar, and put an image behind it???

So, I did this in a blog post, but was told that I'd get more answered in fourms. On my wiki, I want to change the font and size of the text, and put an image behind it. I've seen it done by numerous wikis. Anyone know how? 13:31, December 3, 2012 (UTC)
 * You need to use css for that.—  14:04, December 3, 2012 (UTC)