Right boys and girls this is my problem !!

I have a form setup and what i am trying to do for users, is when they add a new entry they have the option to select or type a product code from the list, this will then generate at the same time the name of the product in the Product name field only, and all other fields will be blank and have to be typed manually.

Now i know its to do with AutoLookup combo boxes but i can't seem to get it to work

Any ideas