Add the pasta to boiling water. After pouring the vinegar, stir it up with a large spoon. Take care that the pasta does not stick to the bottom of the dish. Especially when you boil them in water. If you are having trouble estimating the size you are using. You can use the guide on the pasta package. Lower the stove flame. As long as the pasta is cooked enough. It should be on the stove. And stir it once in a while. This will prevent pasta from sticking.