Basically, you just need to modify your theme’s style.css (WP2.0: Presentation > Theme Editor > style.css), find the blockquote style definition and modify accordingly—that is, adding in the border-left
line between the curly brackets as shown above, or adding the whole blockquote
stuff if there isn’t already one.
Note that there may be more than one blockquote style definition. You can just try each one until it shows correctly. Won’t take much time. Although if you’re interested in playing around with styles and making changes, sooner or later you’re going to have to read up on CSS.
Have a look at WordPress Codex, read the styling and theming sections. There should be pointers to CSS tutorials.
You don’t need to “use” it, as it is a style that gets tied onto all your blockquote
tags. That’s the beauty of style sheets.
PS: If you use the WYSIWIG editor, then just use the “blockquote” icon as per normal. If you write your own html tags in your posts, then just write:
<blockquote>
Your quoted text.
</blockquote>