How output transaction works in Bitcoin?
So what will happen if an output of 1 BTC is available for me to spend, but I want to spend 10 BTC?


If you have 1 USD in your pocket and you want to buy something for 10 USD, you simply can't.

The cited section is equal to: If you have 10 USD and want to buy something for 1 USD the merchant gets 1 USD and you get 9 USD in change.