The site I choose to write about is ebay. I choose to do this site because my mom uses it all the time. She sells items such as antique jewelry, pottery and much more. In order to sell items on ebay you need to set up an account. It wouldn't be a bad idea to set up a pay-pay account because it is easier to receive payments that way. The user must be at least 18 years of age to use ebay. Once you register there is a link that allows you to either begin buying or begin selling; or you could just look at the details of ebay and if you have questions then you can contact ebay to ask them.
If you begin looking for an item to buy and you find one that you are interested in then you either put a bid on it or if it has the option select BuyItNow. Once you purchase an item, with a credit card, check or pay-pal account, you give the seller your address information and you pay them. After they receive payment then they send you what you purchased. After you receive your item you can go and comment on the seller like whether or not they shipped you item fast enough, was the item in the condition they said it was in or were they easy to work with. Each seller has a rating, the better the rating the more chances someone will buy from you.
If you sell an item on ebay then you have to list it. When listing an item you have to take pictures of it, weigh it, give a description of it and tell around how much shipping will cost. Once the auction is over and you receive payment for the item you sold, you have to ship it. When shipping an item, if breakable, make sure the item is securely packaged so it doesn't break.
I know that the experiences my mom has had on ebay haven't been bad at all. However once she sold an item for a neighbor and they accused her of stealing the item even though she showed them proof of sale and gave them the money for the item; she even sold the item for free for them. Most of the time if she puts an item on ebay for someone else she charges them 10% of whatever they make. I don't think that ebay is bad but you have to watch out and be careful of the kind of information that you put on ebay.