To receive notifications when tasks you might be able to help with are posted, keep your schedule up to date in the "Edit Schedule" tab. Just slide the sliders to the earliest and latest time you're available each day.
Even if you don't want to receive notifications (you can turn them off in Settings), please set your schedule. This helps other users tell if anyone is available at the time they'd like when they are posting a new request. But don't worry – your name is not shown, only the number of users, and you are free to accept or ignore any request.