Like ebay

I'm having a prob on ebay. I bought an item from some scum bag in Canada, I paid for it. Well, the payment went to his ex-girlfriend because of an error he made, she declined to accept it. The seller then tells me that I have to re-send the money to him, of course this is a big sum of money, and...

I've never used Ebay and don't know how it works. I'm trying to sell a couple of products and also would like to buy something I have, and don't know how to start. What do I do?

I buy a lot of little things I find on Ebay and it got me wondering. Don't these sellers have to pay taxes on these sales? While I buy just a few items, I noticed that at times they are from the same seller, and they have hundreds of item listed. Thank you.

Let's say I just won my first bid on eBay. What is proper etiquette, normally? Should I pay immediately, or should I wait a few days until I get the product and then pay?

Hello, I need a clear, simple, generic defintion of Ebay in a paragraph or so.. Thanks. seniorpcnanny@aol.com THANK YOU SO MUCH for your help I can't find one anywhere... undefinedundefinedundefined