Atop A Ladder is 1 of 4 Orb Challenges Located in Summer Forest . It is a non-NPC controlled Challenge and can be started by moving to the area where the portals for Hurricos and Sunny Beach are found.
To Complete this challenge; Spyro must know how to climb . Hence, this orb cannot be obtained until Spyro has defeated Crush, arrived in Autumn Plains, and learnt how to climb from Moneybags at the Large Ladders.
This is simply completed by going to where the Hurricos and Sunny Beach Portals are and searching for a ladder around the circular area. If you have not learnt how to climb, Elora should be waiting for you at the ladder. Climb up the Ladder and walk around the edges. The Orb should be on the opposite side of the area as the ladder was.