I’m glad to see you in the Online Community, Othman.
I can help ensure you’ll be able to link OpenCart and add the necessary fields.
The information QuickBooks receives is dependent upon what the third-party application shares with us. For this reason, I recommend getting in touch with OpenCart’s customer support to assist you with the integration process and setting/mapping the fields.
For future reference, I'm adding a link to our online tutorials. These videos can help you run your business using QuickBooks: Video Tutorials.
That should get you started today. If you need any help, feel free to post a comment below. I’d be glad to assist you further. Have a good one.