Review the Achievements on your list. Achievements List tells you what you need to do to complete each task to earn Pages!
 
Under Your Info, tap “View Achievements”.
 
 
Achievements List
 
 
Progress Map:
 
Tap on the Book following your current level. 

You need to collect the required amount of Pages of that Book to level up.
 
 
Note: Tasks on your list are system generated. The count of the task will start upon introducing it to your account.