what methods do eBay use... A button... what tool to pay by? Thanks

ebay is not a subscription service, you pay a fee if you sell items.

it sends you an invoice and eventually just pulls it out of your credit card accout.

First you need to set up a user name . and start buying or selling.
You do not need to pay any fees . until you sell something.
The best way to pay or receive money is paypal, it is also free to set up the account.
You may start buying small cheap items, this way you will gain points in the form of positive feedback . when you have good feedback, people will buy from you more often.
good luck.