Hello,
Thanks for the question. Linking an image and logo to a product is done when you Add a product to OpenCart. Click on the link and you'll see documentation on how this is done. When you're adding the product you have an option for links (e.g. add a link to the manufacturer) and also an option to add an image or images of your product.
I hope that helps to answer your question! Please let us know if you require any further assistance.
Regards,
Arnel C.