You just need to change your Email Settings under the "My Controls" link. Check the box beside "Enable `Email Notification` by default". You can also check the "Enable email notification of replies" when you post a reply to a thread. One final option is to subscribe to that topic, or any topic: click on the options tab on the right corner of your screen and select "track this topic" - this will show up in your "my controls" under subscriptions and if selected will send you email notifications when someone responds to that post.
Hope this helps!