The easiest way to subscribe to a thread you started or post in is to select the check box "Notify me via e-mail when someone replies" just above the OK button you click to submit the message.

Next, click MY ACCOUNT at the top of the page then the FORUM SETTINGS tab and scroll down to "Subscription Preference" and chose how you will receive the messages. You can then click "Thread Subscriptions/MyForums" near the top of this page to further organize your "MY FORUM" selections.