Linking to an image

1. Place your image in the HTML document:

   <img src="image.gif" alt="alt text" />

2. In front of the image tag, add your starting anchor link:

   <a href="URL"><img src="image.gif" alt="alt text" />

3. Add a style to remove the border from the image:

   <a href="URL"><img src="image.gif" alt="alt text" style="border:none;" />

4. Then close the anchor tag right after the end of the image tag:

   <a href="URL"><img src="image.gif" alt="alt text" style="border:none;" /></a>

No spaces between the anchor tag and the image tag. 
If you leave off the style, the image will have a border around it in the default link color.

from http://webdesign.about.com/od/htmltags/ht/htlinkimage.htm