You can find the easy Varrock diary in your achievement list (the trophy tab on the far left of the above screenshot, below the selected Overview tab).
*Area Tasks* category -> *Easy Varrock* subcategory
The diary subcategories are listed in area alphabetical order, and the meta achievements within the Area Tasks category are listed in difficulty order.
While there aren't achievement paths for area task difficulty tiers (closest is the Lumbridge Explorer path, which is a combo of the beginner diary achievements in Lumbridge and some extra Lumbridge achievements salvaged from the 2011 Lumbridge Introductory Tasks tutorial), within the achievement interface you can press the little pin icon next to an achievement to add it to your activity tracker, for ease of reference. (The activity tracker has slots to track up to 5 items at once.)