You'll get emails advising you that you've got an answer to your post if you tick 'email me when I get an answer' when you first post your question. (i.e. you'll be 'subscribing' to your own thread).
You can also have things configured so that you're automatically subscribed to all of your own questions. (To set that up, or to cancel it, click on 'View your profile' and then on 'Edit My Profile'. The relevant check box is at the foot of the page).
You can subscribe to any other thread (so that you're advised whenever there's a new post on it) by clicking on the 'Subscribe' button at the top of the thread.