@ bewa: Hi,
Sorry for the late reply, I've been swamped by other concerns. From your question, I am assuming you have no WP programming experience. If I am wrong, don't take my answer the wrong way :)
You should put this code in your theme's functions.php file.
However, be careful with it, the smallest error can bring down your site.
Before putting any new code in it, make a site backup, so that you can restore your site to the previous state if anything goes wrong or download the functions.php via FTP (if you have access to it). If you make a backup, make sure the backup includes your files not just your database. Please note, that if you make a mistake in functions.php it can make your site inaccessible in both front end and admin, so without FTP access or some other form of access to your wordpress and theme files, you will probably not be able to correct the mistake.
If the instructions above are not something you are familiar with, than it's probably best you don't do it yourself and hire someone with more experience to help you out.
Let me know how it went for you.