no ones laughing Fiona, websites can be frustrating and difficult to understand
however no one can tell you the answer exactly, as we don't own your site.
What you will need to do however is either login to your website control panel and change the code there or do it on your local machine (you home pc) in your website templates if you have them and then upload the changed file to your webhost using a FTP program.
If you give some more information we may be able to hlep you better...did you design your own site, did a friend design your own site, is it a site that you signed up for on the web and then clicked a few buttons etc?