Where is my Data Feed

I am wanting to import my products to Google Merchant Center and it is asking me for my Data Feed details, I am at a total loss as to what this is or how to find it.
If anyone can help me by letting me know where it is on my website or how to create one it would be greatly appreciated.
my store is http://www.offworldcollectables.co.uk/shop/

thanks
sarah

Like this?

http://www.zen-cart.com/downloads.php?do=file&id=1375

Thank you for your response, I have downloaded the add on but I am unsure where to upload all files, do they all get uploaded together to one place or do they have to go into different files?
I think I know how to add the sql but its just the other files adding them from my control panel that confuses me.
Sorry to sound like a complete novice but really new to all this.

Most mods are organized in the correct folders so that all you do is transfer the main mod folder (usually /includes/ or /your_admin/includes/) to the root of your store on the server. The best way to do this is with an FTP client you can download for free, like Filezilla, rather than your server control panel. All decent mods have a readme file which gives exact instructions for that particular mod.