Getting started with Amazon Marketplace is really easy. You don't need to register beforehand. You can create a seller account while listing your first product. If you already have a buyer account on Amazon, you can add your seller account to that.
To register as a seller, you'll need a business name, an address, a display name, a credit card, and a telephone contact number. That's all you need to get started.
To begin, go to the Amazon website, scroll down to 'Make Money With Us,' and then click on 'Sell On Amazon.' You'll see two options: selling a little and selling a lot. The former is for occasional and hobby sellers who expect to sell less than 35 items a month, and the latter is for professional sellers who expect to sell more than 35 items a month.
Selling a little costs 86p plus a referral fee for each sale, and you are limited to the product categories you can sell in. However, there are no ongoing charges if you don't sell very much. Selling a lot costs a 28.75 monthly fixed fee and a referral fee, and you can sell in all Amazon product categories.
If you're unsure, it's recommended to start with the 'selling a little' option and upgrade later. Once you choose your option, simply fill in the online form.