This is a full guide to the second shrine of the Great Sky Island that acts as the Tutorial Area of the game. This is the place that bestows the Combining Ability to Link, which is used to combine various things together to make better weapons and more.
The In Isa Shrine is located to the south of the Ukough Shrine, towards the Western side of the Great Sky Island. It is fairly easy to reach as it is not hidden and is visible from most high places. You will use the Combining ability to clear it.

As soon as you enter the shrine you will get the combining ability. Use this and combine a stick that you would have as a weapon with a boulder lying around. You only need to equip the stick and press a single button after activating the ability to automatically combine them to get a stronger weapon. Use this to break the rocks blocking the way and go ahead.
You will see long stony pillars on the left where the right one will have a chest on top, break it using your weapon to get the chest and open it.
Look towards your right side ahead which will have an opening. There will be a bow and some plants growing Fire Fruit. Pick them all up.
See to the front top side of the room and you will notice a chest on a wooden ramp with leaves covering it. Aim your bow at it but don’t shoot. Follow the combining tutorial and combine your arrow shot with a fire fruit to make it a fire arrow. Then shoot. Then leaves and the wooden ramp will burn and the chest will fall down. Open it and you will get a key.
Go back and open the door with the key to progress ahead. There will be an enemy waiting that you can defeat using your new skills of combining to make powerful weapons or arrows with bonus effects.
Go ahead to the end podium and claim your Light orb to complete the shrine.