Summarize:

You will need a Pokemon who knows Surf to do this. Speak to Celio and he will explain that you need to find an item for his machine. Ember. On the lower right side of the area, you will see some Team Rocket members. You will hear the first password to the Rocket Warehouse. Battle them, and enter the cave. You do not need to read any of the braille charts. You will need a Pokemon with Strength to get through the cave. You can either use an escape rope, use "Dig" or exit the way you came in.
Go to Island 1. Go to the entrance of Mt. Proceed all the way down to the bottom level. Pick up the Ruby and exit.