Hi and welcome to the arena!
To sell just start a thread in For Sale forum and list what you have etc. You can also put a link to your eBay store in your signature so we can just click on it and go there (instead of me wondering if I've ever bought from you).
People like pictures directly embedded in the messages here but for those who are determined enough to click something you can get started with pics by just having a link to whatever web file storage you have already.
The forums are packed with info about working on ponies, the shows, all sorts of things.
Glad you've joined us! Happy ponying!