It's up to you. Explore the island until you know what you need to do.
Those are the little switches you find around certain structures and landmarks. Count them up and put them in the fore chamber by the dock, like the note says.
The Tower is the big mountain behind the library. You can get a good view of it from the gear platform. To rotate it, use the map in the library.
That means you have stumbled on to a clue. Go to the tower to get that clue. "How do I get into the library," you say? That you need to find out yourself. Hint, the door is in the library.
Check for hidden doors in the main rooms. Like other ages, each page is in each brother's room.
Press the middle button and get out. You should now be in front of the tower controls, just like the imager in the Achenar's room. Be sure to note the sound for each direction.
You need to pump the water out. The pump should be easy to find.
You need the contents to finish the game. Write it down exactly as you see it, so when you find the other half you'll be able to get the whole note.
The button that represents the lighthouse. You need to use the telescope to find the degree. Then press the button at that same degree. A little math is required.
Go to the rocky island and play around with the controls. Then use the controls on the pipe to guide the power to the elevator.
Use the stairway next to it. A lever in one of the huts opens the door.
Turn the 5 sounds on and find them on the contraption at the middle island. Then press the bottom button. You need to find them perfectly. If you hear the sound, look at the arrows. If one of them blinks, press it until none of them blink.
It's right of the burning fire landmark.
Use the sounds to guide you. Remember the Mechanical Age? Just go any direction, but if you don't hear a sound anymore, backtrack and go another way.
It's a hard choice. They both say don't touch the green book, but...
Use the 2 pieces of the paper from Stoneship and Channelwood ages.
Only available in realMyst.
Try playing with the image viewer in the dockside chamber again. Particularly the topographical map. Try to walk around the image viewer. Go to the rocket ship area and go along the left side of the walkway. The Rime linking book is revealed above you.
It's pretty cold in the room and the door looks frozen. Try turning on the furnace. If it won't turn on, maybe there's go gas running to it. Still not warm enough? Closing the door would be a good idea.
Related: Official Prima strategy guide (PDF), via Internet Archive