Amazon is a very complex marketplace, there are several policies and different data handling to create NEW products that are not on their catalog or match ASIN against existing products via UPC/EAN codes.
I will Assist you on either type of data creation for Amazon via bulk upload, either delivering files in Text or on Excel files.
Minimum requirements must be forwarded to create or match a listing, such as SKU numbers, UPC/EAN Codes, prices, images, etc. I will assist you detailing what particular data is needed to do a good listing, It is very Clear that is who have more details, your listing will be better described.