Ann explained earlier how to use the Blogger toolbar to create a link when writing a post. But what about creating a link in a comment? Unfortunately, Blogger doesn't give you the same formatting toolbar for comments. But it's pretty easy to learn the basic html that enables you to make a link. Here's the code snippet you need:
<a href="fullURLofyourlink">text you want linked</a>
So if you wanted to link to the afghans for Afghans website, it would look like this:
<a href="http://www.afghansforafghans.org">afghans for Afghans website</a>
this code ends up with this result: afghans for Afghans website
Be sure you put quotes on both sides of the URL, and don't forget the closing tag!