Try you local webpages like craigslist and backpage there is always great answer to any ads placed on these sites and as how old you have to be most places want you to be at least 18 in order to register good luck to you.
Usually you have to be 18 in the UK, to enter into a contract. If you're under 18 maybe a parent or sibling would be happy to help you out. eBay often have "free listing" days. This means that if the item doesn't sell, you don't have to pay a commission/fee.
Otherwise, I'd be looking to Gumtree or Preloved. But before you do anything, check with your parents that they're happy with the idea (assuming you're living at home still).
yard sale helps if you have milkshakes
craigslist
is there any popular websites that dont charge to sell things? there are a few things i have worth money that i would like to sell, also how old do you have to be?
