After your long treck in the desert you'll finally reach the Desert Colossus. There isn't a lot you can do here.
Start by going up to that main building you see in front of you. This is the Spirit Temple. Take a look around. You'll see on one side, a stone that's too big for you to move, and on the other side a hole that's too small for you to crawl through. Screwed.
Walk outside and you'll meet up with Sheik. He will tell you that you need to come back here as a child in order to continue. He will also teach you the Requiem of Spirit, so you can return without wandering through the desert.
Now, before you leave to come back as a child, there is one thing you should do. Here it is:
Now warp yourself back to the Temple of Time, become a child once more, and then warp back here to the Desert Colossus.
As a child it's a good idea to plant the bean plant here while you have the chance. The spot of soil is located just to the left of the Spirit Temple entrance.
Now it's time to do the Spirit Temple.
