Alternatively, if a post has been useful for you, you can click the light bulb icon. This will flag it as valuable information for other members.
If you're interested in a certain thread, you can click the Watch Thread tab, located just above the first post in a thread. You'll receive an alert every time there's a new reply. If you've started the thread yourself, you'll automatically receive alerts when there are replies.
If you're interested in one area of business (say, Legal or Marketing), you can click the Watch Forum tab. You'll receive an alert every time there's a new thread created in the forum.