Actually you don't need to put any code in at all, just the URL.
The forum software makes it a link.

Once you see the link in your post you'll be able to go to 'edit' and replace the linkied words if you want (like your google example).

I will post **http://www.4shared.com/audio/uGkKqE-C/bluxmasmp3.html** below, without the asterisks and the forum will make it a link -
http://www.4shared.com/audio/uGkKqE-C/bluxmasmp3.html


I do not work here, but the benefits are still awesome
Make your sound your own!