How to find out if anyone sent me an answer?

If you are signed in, when a question is answered it will notify you according to your preferences.

If you are not signed in, you will need to save the url of the question page and go back to it regularly to see if it is answered.

If you want to follow a question that you did not add to the site, but that you want the answer to, then use the "follow" link on the left hand menu (you have to be signed in so that it knows where to email you though).