FBA prodcut listing and inventory creation

I have got to a point with creating inventory within Amazon but have become stuck at the point when I try to add products to my inventory. I have about 12 products that I need to add, I have all the details for those products and these are products that already exist on the amazon ecosystem so already have ASIN's. I have authorisation to sell this products in the categories that Amazon has them listed in.

I'm looking for someone to work out how to get these listed on my inventory to the point that I can create FBA labels.

Any questions, just shout,
Cheers,
Drew