So, im totally ignorant when it comes to stuff like this. How exactly does ebay work? How do you actually sell stuff and know that the person buying will pay you the money? I'm assuming that ebay makes a profit on your transaction too... do they take a percentage or something and how does that work? When you post stuff how do you know how much it's gonna cost? do you add postal charges before selling it (how?) or do you just accept that you'll lose a few quid for stamps and stuff?
Also... I was thinking of selling my pedal bike (which I hardly use anymore

Any help appreciated!