you first need to select 10 items that belong to a certain topic. Then you need you click 9 items for the next topic and so on, until at the end you only need to click 1 item.
It is very important to first select as many answers as possible (of which you are 100% sure) and then to skip to the next topic and again select as many answers as possible. This way, you keep on refining to get an ideally maximum score.
In order to create a playlist on Sporcle, you need to verify the email address you used during registration. Go to your Sporcle Settings to finish the process.