We can sell what we want in sell option. There should be a tag button in the shop option.
Everybody can sell their things at 50 coins or above(50 is the cheapest and highest is something I can't imagine.)Players will get a notification if their item is sold. I don't usually buy the things in the normal shop because are so expensive so sale option is a nice option for cheap things.There shall be a friends page also where you can follow a player and also have a chat with them in the chat box(a notification will be send to them every time someone follows them on this friends page).There shall be also this challenge page where challenges are "have 15 friends/followers", "have 10 clothing items in which five of them are bought for free/ad and the rest five with coins", etc etc.