What happens behind-the-scenes in LONG and SHORT orders while Futures Trading?

I would like to know what actually Binance does behind-the-scenes LONG and SHORT orders while Futures Trading

Let say I have $100 and price of a coin is also $100

My understanding about Buy/Long is that if I take 10x Leverage that means I am borrowing $900 from Binance and my total balance becomes $1000 and then price of coin goes up, and I sell it, binance takes its $900 back and I get all profit excluding some binance fees.

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What happens in Short order?