I purchased a stock but sadly forget to sell at a very good timing because its quarterly report indicates its benefit below expectation.
But the time that report was released is not in the trading hours.
So here is what I see:

I am very new to stocks trading and I have no idea what After Hours price stands for.
What would happen if I sell the stock tomorrow while market is opened? Say if I request an order to sell the stock at market price, it'd be sold at < 18.76USD?
Thanks,