To register an eBay seller user, you can follow the steps below:

1. Visit the eBay website: https://www.ebay.com/ and click the "Register" button in the upper right corner.

2. Select the registration type: On the registration page, select "Personal Account" or "Business Account". If you are an individual seller, select "Personal Account" and if you are a business seller, select "Business Account".

3. Enter personal information: On the next page, enter your personal information such as name, address, and email address. Please make sure to enter accurate information so that eBay can send your sales information to you.

4. Verify your email address: After entering your email address, eBay will send you a verification email. You need to click the link in the email to verify your email address.

5. Set your account information: After verifying your email address, you need to set your account information, including username and password. Please make sure your password is safe and reliable to prevent your account from being stolen.

6. Start selling: After completing the registration, you can start selling goods on eBay. You need to set your payment method, shipping method, return policy and other information.

It should be noted that to register an eBay seller account, you need to provide real personal information, such as name, address, etc., and you need to comply with eBay's relevant regulations and policies.