First read the instructions carefully and see if you can do the task and understand what the task author is asking you to do. You will start with the zero level tasks, after doing a set of these, you will get a level badge and more tasks will be available to you. (Zero level tasks mostly appear after midnight in Pakistan). Try not to attempt the task if the instructions are not clear or you are not sure. Also subscribe the zero level task forum to get notified of new tasks.
Try your first task and you will slowly understand everything.