Amazon seller account setup

I am looking for an experienced individual or team to help me set up my Amazon seller account. I'm not sure if an individual or professional account would serve my needs best, so guidance from someone familiar with the Amazon system would be required. Additionally, I'm unsure if I need assistance with inventory management, and so I am open to suggestions on that front. Lastly, I do need help listing products to ensure that I have a comprehensive store that customers can find and purchase from easily. If there are any additional services you can provide that will help me maximize sales on Amazon, please let me know. I do have an account setup with products listed
However I cannot get any further to add barcodes etc .