People have to send what they sell themselves, usually using mail. They can transfer the money in any way they want. A lot of people use PayPal to transfer the money. PayPal is owned by the same people as eBay. Margaret Whitman is the current CEO of the company.
eBay was started in 1995 by Pierre Omidyar. It was first called Auctionweb. The name 'eBay' came later when he tried to register a domain name for his planned name EchoBay. It was already taken so he shortened the name to 'eBay'.
Millions of items are bought on eBay every day. It is very cheap to list an item on eBay. Many people look at others' items because they are interested in them.