You are in Sri Lanka and your country has some unique laws about selling on eBay. Prior to selling anything you need to register with your government as a business. You will also need a Payoneer account to be able to get paid once you start selling.
If you are going to sell internationally you need to become familiar with your countries laws on exporting and international laws pertaining to importing items. You will need to be able to handle basic math and understand your cost of doing business to be able to make a profit. Do some market research to be able to figure out if you can be competitive at selling and what products you are going to sell. Read and understand the eBay money back guarantee and what it means to you as a seller.
https://www.ebay.com/help/policies/ebay-money-back-guarantee-policy/ebay-money-back-guarantee-policy...
Avoid drop shipping items out of China as many Sri Lankan's appear to be doing, it is a poor business model. Once you have all of that then.
https://www.ebay.com/help/selling/selling/start-selling-ebay?id=4081
