Here are some images that might help. Clear all secret tiles before you proceed.
A lot of players have said that their screen doesn't have the portal activation buttons. If that is the case, you can either manually move the 100 energy stone through, or contact Support.
If you decide to move it yourself, here is a diagram showing the path to follow and whether to push vs. pull.
Make sure you clear the areas that I've marked with orange. Those are places you will need to circle around to get to the proper side of the stone.