I have created the following link class to affect certain links and not all:

a.thumbhead:link {font-family: Verdana, Arial, Helvetica, Arial, sans-serif;
font-size: 12pt;
font-weight: bold;
color: #838ffc;
text-decoration: underline; }

I was planning to use it <a class=thumbhead> some link</a> to have desired effects on some links that are dynamically generated. But somehow this thing is not working. I need some help

<a href="what you are linking to" class="thumbhead">some link</a>

the href is required for the a tag

Take out the :link part in your CSS. It's not needed.

Not unless you're also going to use other pseudo classes