If you're having troubles finding the items required to upgrade your Hero, you can view exactly where the items can be found by tapping on the item when viewing the profile of the Hero. After tapping on the item, you are sent to a screen that displays where the item can be found. Here you can tap on the yellow arrow button to go directly to the mission or location where the item can be found.
How do I find the items required to increase the grade of my hero?
