How do I get started on selling my original product on amazon?

My dad and I have an Etsy shop that has been fairly successful he’s insisting on starting a shop on amazon. I made a seller account, filled everything out, put in all the tax information. Now I’m stuck at the point of not knowing how to even post a listing. I have no idea how to get started and it’s been a little overwhelming. Our product is graphic tees we make them to order on Etsy, we buy the shirts and print the designs on them and people pick out from the listings we have up on the shop. I’m not even sure Amazon would be right for us but my dad is persistent about selling on there and he’s basically leaving all the shops set up and maintaining to me. This is very overwhelming given that I have zero experience in any of this aside from setting up the Etsy shop which was a lot more straightforward than Amazon. I would appreciate someone telling me how to get started or showing me what the next step is. Thank you.