On the main page of Blurtit.com, click "Topics" located in the top right-hand corner.
The left column will show you all the questions that exist for all the topics. You can sort these out by clicking on "Unanswered" to see questions that have no answer, so that you can contribute answers. And on the right column, you'll see all the topics that exist on the site.
So let's say you're an expert on Business and Finance. Click on the topic and click "Follow", located right below the picture icon on the right. What will following a topic do? If you click the drop-down menu next to your profile (top right corner), click on "Your Topics" and you'll see Business and Finance there. So whenever you visit this website, you can go straight to Your Topics and click on that topic to quickly answer questions on there.