[url=URL]Name of URL[/url]
If you want to link to other pages you use this bbcode. You will notice that included URLs in your text will be automatically converted into links (if you used the related option).
A text with an [url=index.php]internal link[/url] and an [url=http://www.woltlab.com]external link[/url].
A text with an internal link and an external link.