Newb question.... If I sold some shares in the auction and the...

Newb question.... If I sold some shares in the auction and the order was partially filled then what happens?

If the stock opens lower tomorrow I guess I have missed the selling price on the remaining shares and need to amend the price if I want to off load the full amount?

If I cancel the order I assume the partially filled still go through?

How does brokerage work assume one fee either when the final amount settles or when the order is cancelled?

Thank you.