I'm not going to go through Schedule D line by line. All I want to do is give you an overview so that what you are doing makes sense. It's really a very simple and logical form once you get the big picture. And how much did you make or lose on the transaction. Short term means the stock was held for less than a year.
Long terms means it was held for more than a year.
Here's how you tell. You have to hold it at least one day beyond the date on which you bought it to qualify for long-term status. Uncle Sam doesn't count the purchase day, which makes sense. If you bought on the 4th and sold it the next day, on the 5th, you've really only owned it for one day, not two. No break for leap years.