I've been hacked...plz help

http://www.theyateskids.com/guestbook/index.php

I've been hacked and I am an amatuer. I do not know how to fix. Can some wise person help me?

I have removed the posts. It was not easy given that the works proxy kept killing my connection due to the amount of bad language in your guestbook. Patch it now. http://www.carbonize.co.uk/Board look in modifications for the patch.

I thank you and apologize for the language. The band that I do the site for are a little foul mouthed.

No need to apologise. My works proxy seriously sucks. I can only view websites that use port 80, No websites that are IP's, to many bad words and the connection is cut, if the site is on their banned list the connection is cut. Really pathetic it is. My old webhosts domain was banned as apparently containing pornographic content.