i wish someone could explain to me this in english, I understand that a short is betting that it will go down, long the opposite, but how does it work in detail? can someone give me an example? like they were explaining it to a 5 year old? lol.

Why does it matter that there are 7300 shorts? because thats a shit ton?
Short: Somebody borrows bitcoins and sells them. Later he will buy bitcoins at lower price and returns them to the lender + interest.
Long: Borrow $$ then buy BTC and sell them later.
On Bitfinex, they have a claim option. If you buy 10 coins at $100, and the price goes up $20, you have $200 profit (10 coins x 20 USD).
You can sell 8 coins, and use the $200 profit to "claim" the remaining 2 coins at the original $100 price.
This means you don't necessarily have to sell all of the original 10 coins.