Google Product Category - where is input field?

Hello,

Product feed to Google Merchant is working fine, except for the requirement to show a Google Product Category. I know what this is, but cant see where the data field is on Opencart to put it in.

Advice please?

I cant be the first to ask this, but my search has not given me an answer.

Thanks very much

Graeme

Bought an extension to fix

G