Additional field optional?

Hi!

Very sorry if this has been asked and answered before.

I have added an additional field to my news called {link}.

See code:

<div class='codetop'>CODE</div><div class='codemain' style='height:200px;white-space:pre;overflow:auto'><div style="float: right;">(info)</div></div>

I would like it to only appear when this additional field is used / has content. How would I code this?

Thanks in advance.