Making a TD clickable

The href property is designed for anchor elements (<a/>). "ahref" as you've put should be <a href="">. a is an element of its own, not a HTML attribute, and href is an attribute it accepts.

To make the text of a td clickable you can simply put an anchor within it:

<td>
    <a href="#child4">My clickable text</a>
</td>

Edit: To fix this now that the question has been added, simply add in the following CSS:

td a {
    display:block;
    width:100%;
}

What this does is display the anchor tag as a block, allowing us to adjust the width, and then set the width to 100%, allowing it to fill the remaining space.

Working JSFiddle.

Add the onClick event on the td mark.

<td onClick="document.location.href='http://www.yoursite.com';"> some text here </td>

There is a very simple way of doing this with just HTML. Put the link text inside a DIV. The DIV occupies the whole TD and makes it all clickable.

<a href="http://whatever.com">
  <div>
     Link Text
  </div>
</a>