You want to follow an interesting topic? No problem - you can turn on or off the notifications on any new reply (subscribe / unsubscribe) in the header of the respective topic. Just look for the 
-icon in the upper right corner.
If you create a new topic, you can also check the box there before submitting your thread to be notified about new replies.
You can also manage all your subscriptions in your profile settings. Just go to:
Quick-Links
MY PROFILEFORUMSSUBSCRIPTIONS