You have: <a class="a" href="">
You need to add the link in the "" after href. Also I don't know that you need "<a class="a".
Here is a sample from one of my eBooks: <a href="http://www.HarlequinMoreThanWords.com">www.HarlequinMoreT hanWords.com</a>
So yours should look something like this:
<a href="
ADD THE LINK HERE">To sign up click here!</a>